Erythrocyte deformability, plasma lipid peroxidation and plasma protein oxidation in a group of OSAS subjects.

Considering that obstructive sleep apnea syndrome (OSAS) is usually associated with endothelial dysfunction, atherosclerosis and cardiovascular disorders, our aim was to examine the erythrocyte deformability and the oxidative status in a group of OSAS subjects. We consecutively enrolled 48 subjects with OSAS defined after a 1-night cardiorespiratory sleep study, subsequently subdivided according to the apnea/hypopnea index (AHI) value in two subgroups: Low (L = 21 subjects with AHI<30) and High (H = 27 subjects with AHI>30). We evaluated the erythrocyte deformability, expressed as elongation index (EI) and the parameters of the oxidative status, such as lipid peroxidation (expressed as thiobarbituric acid-reactive substances - TBARS) and protein oxidation (measured as carbonyl groups - PC). In the entire group and in the two subgroups of OSAS subjects we found a decreased erytrocyte deformability at all shear stresses, not correlated with the plasmatic oxidative stress nor with the polysomnographic parameters. Lipid peroxidation was increased in the whole group and in the H subgroup of OSAS while protein oxidation showed a different trend. As in OSAS the osmotic fragility and the metabolism of the red cells seem to be not impaired, the oxidative damage to the red cell membrane proteins might be responsible for the reduced erythrocyte deformability. This rheological alteration, in addition to the increase in whole blood and plasma viscosity and to the erythrocyte hyperaggregation, could influence the microcircolatory profile in OSAS subjects.

Analysis of the correlations between oxidative stress, gelatinases and their tissue inhibitors in the human subjects with obstructive sleep apnea syndrome.

Obstructive sleep apnea syndrome (OSAS) is commonly associated with endothelial dysfunction, atherosclerosis and cardiovascular disorders. On the basis of this observation, our aim was to examine the oxidative status and the matrix metalloproteases (MMP) profile in a group of subjects with OSAS. We enrolled 48 subjects with OSAS defined after a 1-night cardiorespiratory sleep study, who were subsequently subdivided in two subgroups according to the severity of OSAS (low grade = L-OSAS; high grade= H-OSAS). We measured the parameters of oxidative stress, such as lipid peroxidation, protein oxidation, total antioxidant status (TAS), nitric oxide metabolites (NOx), and the plasma concentrations of the gelatinases (MMP-2 and MMP-9) and their tissue inhibitors (TIMP-1 and TIMP-2). We found a significant impairment of oxidative status in H-OSAS compared to L-OSAS and higher plasma levels of MMP-9 and TIMP-1 in H-OSAS compared to L-OSAS. In this study we observed a positive correlation between TBARS and MMP-9, a positive correlation between PC and MMP-9, and a negative correlation between NOx and MMP-9, especially in the whole group of OSAS subjects. These data underline how strong interrelationships among some parameters of the oxidative stress, in particular those reflecting lipid peroxidation, protein oxidation and NOx, and MMP-9 are evident in OSAS subjects. All these information may be useful in the clinical practice keeping in mind the cardiovascular complications generally accompanying the obstructive sleep apnea syndrome.

Protein carbonyl groups in trained subjects before and after a cardiopulmonary test.

Physical exercise influences the body's oxidative status. The modifications can involve lipids, proteins and nucleic acids, and different effects seem to be induced by regular and acute exercise respectively. We examined protein oxidation, expressed as concentration of protein carbonyl groups (PC), in trained subjects before (time 0), 10 min (time 1) and 24 hours (time 2) after a cardiopulmonary test performed on a cycloergometer. We enrolled 38 trained subjects (26 men and 12 women), subdivided in two groups (A1 and B1) of 19 subjects each, according to the median value of VO2max, and in two groups (A2 and B2) of 19 subjects each, according to the median value of PC at baseline. PC concentration was measured by an enzyme-linked immunosorbent assay (ELISA). The groups A1 and B1 did not differ from each other as regards the basal PC level and groups A2 and B2 were not different as regards the VO2max. At time 1 PC showed a significant increase in comparison with baseline in trained subjects as a whole group, as well as in each subgroup. At time 2, PC were decreased in comparison with both times 0 and 1 in the whole group and in subgroups A1 and B2, whereas in subgroups A2 and B1 the PC value at time 2 was not different compared to time 0. The percentage increase of PC at time 1 vs time 0, as well as the percentage decrease at time 2 vs time 1 and time 0 respectively, were not different between subgroups A1 and B1. On the contrary, the percentage variations observed at each interval were significantly different between subgroups A2 and B2. The results suggest a reaction of antioxidant systems to acute exercise in trained subjects, influenced by basal PC levels more than by aerobic fitness.

Lipid peroxidation and protein oxidation are related to the severity of OSAS.

OBJECTIVE: Obstructive sleep apnea syndrome (OSAS) is associated with elevated cardiovascular morbidity and mortality. Considering that oxidative stress is involved in endothelial dysfunction and atherosclerosis development, our aim was to examine lipid peroxidation and protein oxidation, two parameters of oxidative status, in a group of subjects with OSAS. PATIENTS AND METHODS: We consecutively enrolled 48 patients (36 men and 12 women; mean age 49.7±14.6 yrs) with OSAS, subsequently subdivided according to the apnea/hypopnea index (AHI) value in two subgroups: Low (L= 21 subjects with AHI<30) and High (H= 27 subjects with AHI>30). We examined lipid peroxidation, expressed as TBARS, and protein oxidation, measured as carbonyl groups in plasma samples from fasting venous blood. RESULTS: We observed that TBARS and carbonyl groups were significantly higher in subjects with AHI > 30 in comparison with the L subgroup and the whole group of OSAS subjects. In addition, we found that these parameters were positively correlated with neck and waist circumference, with the AHI value and with the oxygen desaturation index, and negatively correlated with the mean oxygen saturation. CONCLUSIONS: Lipid peroxidation and protein oxidation in OSAS patients are significantly correlated with the severity of the disease.

Nitric oxide metabolites (nitrite and nitrate) in several clinical condition.

We determined the concentration of nitric oxide metabolites (NO2-+NO3-), expressed as NOx, in several clinical conditions. Regarding this, we have examined 25 subjects with arterial hypertension, 41 subjects with chronic kidney disease in conservative treatment, 106 subjects with metabolic syndrome subdivided according to the presence (n = 43) or not (n = 63) of diabetes mellitus, 48 subjects with obstructive sleep apnea syndrome (OSAS), 14 women with systemic sclerosis complicated with Raynaud's phenomenon, 42 dialyzed subjects and 105 young subjects with acute myocardial infarction (AMI). In subjects with arterial hypertension, chronic kidney disease, metabolic syndrome, systemic sclerosis, as well as, in dialyzed and AMI subjects, we found at baseline a NOx increase. In dyalized subjects after a standard dialysis session, we observed a decrease in NOx. The increase in NOx in juvenile AMI was significantly influenced by cigarette smoking and less by cardiovascular risk factors and the extent of coronary lesions; at 3 and 12 months later than the initial event, we observed a decrease of NOx that remains significantly higher than the control group. In subjects with OSAS no difference in NOx was noted in comparison with normal controls, although their subdivision according to the apnea/hypopnea index operates a clear distinction regarding NOx concentration.

Influence of a new bicycle crank design on aerobic parameters of non-cyclists.

AIM: A well known problem in conventional cycling crank systems is the pedalling dead spot when the crank arms are in vertical position. The pedalling dead spot mitigates the power output during the propulsion phase of pedalling. The aim of this study was to verify the effects of a new design of crank system on aerobic parameters of performance in healthy non-cyclists. The mechanical concept of the new system is based on the theory that crank arms should never be perpendicularly aligned to the ground at dead spot. METHODS: The maximal aerobic capacity (VO2 max) and different parameters of cycling efficiency were measured in 14 (mean±SD of age: 26±5) non-obese (body mass index: 26.0±3.0 kg/m2) healthy men in two different occasions at intervals of 2 days using alternately and in randomized order both the traditional crank system and the system without dead spot respectively. RESULTS: The workload performed was significantly higher with the new crank system as suggested by the higher exercise duration (12.89 ±2.36 vs. 13.33±2.30 min; P=0.032). CONCLUSION: The favourable results obtained in this study using the new chainring may be in consequence of a more efficient biomechanics of pedalling that does not reflect changes in O2 consumption and CO2 produced. However, it is not possible to exclude that involuntary motivational factors may have induced the difference in the time test since it was not possible to blind subjects about the two crank systems. Further investigations are necessary to confirm the results of this exploratory study and give a more exhaustive explanation about the mechanisms that allow the possible better performance with this new chainring system.

Protein carbonyl groups in trained subjects.

The purpose of this research was to evaluate the plasma protein carbonyl groups (PC) in 81 trained subjects (TS) who practiced regular, non professional physical activity. They were divided into three groups according to the type of sport they practiced (endurance, mixed or power). On fasting venous blood we examined the PC groups employing an enzyme-linked immunosorbent assay (ELISA) kit, in which 2,4-dinitrophenyl-hydrazine reacts with the PC forming a stable hydrazone product. In the whole group of TS a significant decrease in PC was present, in comparison with sedentary controls (SC). Dividing TS into groups, we observed a decreased PC concentration in those practicing endurance and mixed sports, but not in those practicing power sports. There was no difference between men and women for PC either in SC or in TS; male TS had a PC concentration significantly lower than male SC. Our data show that body proteins are more protected against oxidative stress in subjects who practice endurance and mixed sports. These results give further support to the promotion of regular physical activity including aerobic exercise.

Deep venous thrombosis: behaviour of the polymorphonuclear leukocyte integrin pattern at baseline and after in vitro activation.

In a group of 18 subjects with acute deep venous thrombosis (DVT), evidenced by clinical examination and echo-color-Doppler, we examined the phenotypical expression of the polymorphonuclear leukocyte (PMN) beta2-integrins (CD11a, CD11b, CD11c, CD18), obtained by using a flow cytofluorimeter. The evaluation was performed before and after in vitro activation (prolonged for 5 and 15 minutes) with 4-phorbol 12-myristate 13-acetate (PMA) and N-formyl-methionyl-leucyl-phenylalanine (fMLP). In DVT subjects, at baseline, the phenotypical expression of CD11b was decreased and that of CD11c was increased when compared with normal controls; no difference was found in CD11a and CD18 expression. In normal subjects PMN activation with both activators led to a constant increase of all PMN adhesion molecules; in DVT subjects CD11b, CD11c and CD18 increased, while CD11a expression did not show any change. These data indicate the presence of a functional alteration in circulating PMN cells from patients with DVT.