Utility of ultrasound assessment of diaphragmatic function before and after pulmonary rehabilitation in COPD patients

Background

Pulmonary rehabilitation (PR) may improve respiratory symptoms and skeletal muscle strength in patients with COPD. We aimed to evaluate changes in ultrasound (US) measurements of diaphragmatic mobility and thickness after PR in COPD patients and to test its correlation with PR outcomes.

Methods

Twenty-five COPD patients were enrolled and underwent a diaphragm US assessment before and after a 12-week PR program.

Results

We found a correlation between the intraindividual percentage of change in the diaphragmatic length of zone of apposition at functional residual capacity (ΔLzapp%) and the change in 6-minute walking distance (6MWD) after PR (rho=0.49, P=0.02). ΔLzapp% was significantly higher in patients with improved 6MWD and COPD Assessment Test (CAT) score (mean rank=12.03±2.57 vs 6.88±4.37; P=0.02). A ΔLzapp% of ≥10% was able to discriminate among patients with improved 6MWD, with a sensitivity of 83% and a specificity of 74%. The area under the receiver operating characteristic curve for ΔLzapp% was 0.83. A cutoff value of ≥9% of ΔLzapp% had a positive predictive value in discriminating a reduction in ≥2 points of CAT score after PR, with a sensitivity and a specificity of 80% and 62%, respectively.

Conclusion

Diaphragm US assessment represents a useful prognostic marker of PR outcomes in COPD patients.

Moderate weight loss decreases oxidative stress and increases antioxidant status in patients with metabolic syndrome

Background. Oxidative stress is enhanced in metabolic syndrome (MetS) and believed to contribute to accelerated atherosclerosis. Weight loss is associated with lowered oxidative stress. Methods. We performed a cross-sectional study in 92 consecutive patients with metabolic syndrome and 80 without. A dietary intervention with moderately low-calorie diet (600 calories/day negative energy balance) was carried out in 53 of metabolic syndrome patients. Oxidative stress, assessed by sNOX2-dp and urinary 8-iso-PGF2α, and antioxidant status, assessed by serum levels of vitamin E and adiponectin, were measured before and after 6 months. Results. Serum vitamin E/cholesterol ratio was significantly lower in metabolic syndrome compared to controls (P < 0.001) and decreased by increasing the number of metabolic syndrome components (P < 0.001). After six months, 23 and 30 patients showed >5% (group A) or <5% (group B) weight loss, respectively. Urinary 8-iso-PGF2α (−39.0%), serum sNOX2-dp (−22.2%), adiponectin (+125%), and vitamin E/cholesterol ratio (+129.8%) significantly changed only in A group. Changes in body weight and in serum adiponectin were independent predictors of vitamin E/cholesterol ratio variation. Conclusion. Our findings show that in metabolic syndrome moderate weight loss is associated with multiple health benefits including not only oxidative stress reduction but also enhancement of antioxidant status.

Weight loss is associated with improved endothelial dysfunction via NOX2-generated oxidative stress down-regulation in patients with the metabolic syndrome

The aim of this study was to assess whether adherence to a restricted-calorie, Mediterranean-type diet improves endothelial dysfunction and markers of oxidative stress in patients with metabolic syndrome. A moderately low-calorie (600 calories/day negative energy balance), low-fat, high-carbohydrate diet (<30% energy from fat, <10% from saturated fat and 55% from carbohydrate) was prescribed to 53 outpatients with the metabolic syndrome. Participants were divided into two groups according to body weight loss > or < 5% after 6 months. Group A (n = 23) showed a remarkable decrease in body weight (-6.8%), body-mass-index (-4.6%), waist circumference (-4.8%), HOMA-IR (-27.2%), plasma glucose, glycosylated haemoglobin, total and LDL-cholesterol, blood pressure, serum NOX2 (the catalytic core of NADPH oxidase) (-22.2%) and urinary8-isoprostanes (-39.0%) and an increase of serum NOx (Nitrite/Nitrate) (+116.8%) and adiponectine (+125.5%) as compared with those in group B (n = 30). A statistically significant increase in brachial artery flow-mediated dilatation was observed in group A (+24.7%; p < 0.001), while no changes were present in group B. Variations of flow-mediated dilatation were statistically and negatively correlated with changes of serum NOX2 levels (p = 0.04), body-mass-index (p < 0.01), waist circumference (0.01), glycosylated haemoglobin (p < 0.01), LDL-cholesterol (p < 0.01) and triglycerides (p < 0.05) and positively correlated with changes of serum NOx (p < 0.001) and adiponectin (p = 0.01). The results show that moderate weight loss is able to improve endothelial dysfunction in patients with the metabolic syndrome. The coexistent decrease of NOX2 activation suggests a role for oxidative stress in eliciting artery dysfunction.

NOX2 up-regulation is associated with artery dysfunction in patients with peripheral artery disease

OBJECTIVE

Oxidative stress seems to play a role in impairing flow-mediated dilation (FMD) in patients with peripheral artery disease (PAD) but the underlying mechanism is still undefined. We evaluated whether NOX2, the catalytic core of NADPH oxidase, the most important producer of reactive oxidant species (ROS), is implicated in impairing FMD.

METHODS

We measured FMD, urinary isoprostanes, a marker of oxidative stress, nitric oxide generation by serum levels of nitrite/nitrate (NOx), and serum levels of soluble NOX2-derived peptide (sNOX2-dp), a marker of NOX2 activation, in 50 PAD patients and 50 controls. Also, we performed an interventional cross-over study to assess if propionyl-L-carnitine (PLC) (6g/day), vs. placebo, was able to affect FMD via an oxidative stress-mediated mechanism.

RESULTS

Compared to controls, patients with PAD had enhanced sNOX2-dp and isoprostanes and reduced NOx and FMD. Multiple linear regression analysis showed that FMD was independently associated with sNOX2-dp. After PLC infusion FMD increased while sNOX2-dp and isoprostanes significantly decreased; no changes were observed after placebo. In vitro study by incubating platelets or white cells with PLC demonstrated a significant inhibition of p47(phox) translocation on cellular surface and ROS generated by NOX2 activation.

CONCLUSION

This study suggests that in PAD patients ROS generated by NOX2 contribute to reduce FMD and that the administration of an antioxidant is able to improve arterial dilatation via NOX2 inhibition.

NOX2-mediated arterial dysfunction in smokers: acute effect of dark chocolate

BACKGROUND

Cocoa seems to exert artery dilatation via oxidative stress inhibition but the mechanism is still unclear.

OBJECTIVES

To investigate whether in smokers, dark chocolate elicits artery dilatation via down-regulation of NOX2, the catalytic core of NADPH oxidase.

METHODS

Flow-mediated dilatation (FMD), oxidative stress (as assessed by urinary isoprostanes excretion), nitric oxide generation (as assessed by serum levels of nitrite/nitrate (NOx)), NOX2 activity (as assessed by blood levels of soluble NOX2 derived peptide (sNOX2-dp)) and serum epicatechin were studied in 20 smokers and 20 healthy subjects (HS) in a crossover, single-blind study. Patients were randomly allocated to 40 g dark chocolate (>85% cocoa) or 40 g of milk chocolate (≤35% cocoa). FMD, urinary isoprostanes, NOx and sNOX2-dp were assessed at baseline and 2 h after chocolate ingestion.

RESULTS

Smokers had lower FMD and NOx and higher sNOX2-dp compared to HS. After dark chocolate intake, urinary isoprostanes and sNOX2-dp significantly decreased and FMD and NOx significantly increased in smokers but not in HS. No changes of the above variables were observed after milk chocolate intake. Multiple linear regression analysis showed that in smokers the only independent predictive variable associated with a change in FMD was a change in sNOX2-dp. Serum epicatechin increased in either group only after dark chocolate intake, reaching values higher than 0.1 μM. Platelets from smokers (n=5), but not from HS (n=5), showed lower p47(phox) translocation to platelet membrane and higher NOx when incubated with 0.1-10 μM epicatechin.

CONCLUSION

Results suggest that in smokers, cocoa enhances artery dilatation by lowering of NOX2 activation.

Obstructive sleep apnoea syndrome and the metabolic syndrome in an internal medicine setting

BACKGROUND

Obstructive sleep apnoea syndrome (OSAS) is widely accepted as a cardiovascular risk factor. Lately it has been considered in turn as both a component and one of the causes of the metabolic syndrome (MS).

METHODS

We studied 281 heavy snorers of both sexes consecutively attending a metabolic clinic. Aim was to evaluate the association of OSAS and MS in a large series of patients within an internal medicine setting. Patients underwent a clinical and biochemical work up and performed unattended polysomnography.

RESULTS

Of 226 non-diabetic snorers, 48 had primary snoring; 54 mild, 51 moderate, and 73 severe OSAS. A positive association was found between OSAS severity, central obesity indices and the mean metabolic score (p=0.016). Prevalence of hypertension increased with OSA severity (p=0.010). Polysomnographic indices were correlated with the metabolic score, insulin levels and central obesity indices. At regression analysis, male sex (t=3.92; p=0.000) and waist circumference (t=3.93; p=0.000) were independently associated with AHI (apnoea/hypopnoea index), while ODI (oxygen desaturation index) and waist circumference were the independent predictors (t=2.16; p=0.033 and t=3.74; p=0.000 respectively) of the metabolic score. Prevalence of OSA was 83% in 55 patients with diabetes and 34% had severe OSA. Almost all diabetics with OSA had MS. The metabolic score was higher in diabetic OSA as compared to non-diabetic OSAS (p=0.000).

CONCLUSIONS

Our findings show a high prevalence of OSAS among patients referred to a metabolic outpatient clinic because of suspected metabolic disorders and heavy snoring and suggest a strong bidirectional association between OSAS and MS.