Quantification of SARS-CoV-2 monoclonal IgG mass fraction by isotope dilution mass spectrometry.

The availability of serology assays to measure antibodies against the SARS coronavirus 2 (SARS-CoV-2) expanded rapidly during the Covid-19 pandemic. The interchangeable use of such assays to monitor disease progression and immune protection requires their standardization, for which suitably characterized monoclonal antibody materials can be useful. The methods, based on isotope dilution mass spectrometry, to value assign the mass fraction of such a material in solution within the context of an international interlaboratory comparison study (CCQM-P216) are described. The mass fraction in solution of a humanized IgG monoclonal antibody (mAb) against the SARS-CoV-2 Spike glycoprotein in the study sample has been value assigned through a combination of liquid chromatography, isotope dilution mass spectrometry (LC-ID-MS) methods and size exclusion chromatography with UV detection (SEC-UV). The former were developed for the quantification of amino acids and proteotypic peptides as surrogate analytes of the mAb while the latter was applied for the determination of the relative monomeric mass fraction. High-resolution mass spectrometry (hrMS) allowed the molecular weight evaluation and ruled out the presence of significant impurities. Method trueness was assessed using a subclass homologous IgG1 material value assigned by amino acid analysis. The assigned mass fraction of monomeric SARS-CoV-2 IgG in solution was 390 ± 16 mg/g. The associated expanded uncertainty originated mainly from acid hydrolysis variability and Trypsin/Lys-C digestion variability and efficiency.

Acid-base balance during repeated cycling sprints in boys and men.

The aim of this study was to investigate the acid-base balance during repeated cycling sprints in children and adults. Eleven boys (9.6 +/- 0.7 yr) and ten men (20.4 +/- 0.8 yr) performed ten 10-s sprints on a cycle ergometer separated by 30-s passive recovery intervals. To measure the time course of lactate ([La]), hydrogen ions ([H(+)]), bicarbonate ions ([HCO(3)(-)]), and base excess concentrations and the arterial partial pressure of CO(2), capillary blood samples were collected at rest and after each sprint. Ventilation and CO(2) output were continuously measured. After the 10th sprint, concentrations of boys vs. men were as follows: [La], 8.5 +/- 2.1 vs. 15.4 +/- 2.0 mmol/l; [H(+)], 43.8 +/- 1.3 vs. 66.9 +/- 9.9 nmol/l (P < 0.001). Significant correlations showed that, for a given [La], [H(+)] was lower in the boys compared with the men (P < 0.001). Significant relationships also indicated that, for a given [La], [HCO(3)(-)] and base excess concentration were similar in the boys compared with the men. Moreover, significant relationships revealed that, for a given [H(+)] or [HCO(3)(-)], arterial partial pressure of CO(2) was lower in the boys compared with the men (P < 0.001). The ventilation-to-CO(2) output ratio was higher in the boys during the first five rest intervals and was then higher in the men during the last five sprints. To conclude, during repeated sprints, the ventilatory regulation related to the change in acid-base balance induced by lactic acidosis was more important during the first rest intervals in the boys compared with the men.

Chemical and nonchemical stimuli during breath holding in divers are not independent.

In the breath-hold model described by S. Godfrey and E. J. M. Campbell (Respir. Physiol. 5: 385-400, 1968), chemical and nonchemical stimuli are independent. Because these two factors are time dependent, the effect of each could not be measured by breath-holding time (BHT). The aim of this study is to dissociate chemical and nonchemical stimuli and to assess the effects of BHT and PCO2 on respiratory center output by measurement of occlusion pressure (P0.1) and mean inspiratory flow (VI). Nine well-trained divers (age 36.5 +/- 5.0 yr) took part in the study. Each subject had to hold his breath at 75% of vital capacity for 30, 50, and 70 s of BHT. Before each breath hold, the subject inspired successively two vital capacities of the same CO2-O2 gas mixture. P0.1 and VI were measured during the first reinspiration after the breath hold. For the same BHT, we observed good linear relationships between P0.1 or VI and alveolar PCO2. The slopes of these relationships increased with BHT. For alveolar PCO2 of > 50 Torr, P0.1 increased linearly with BHT. These results indicate that, during breath holding, chemical and nonchemical stimuli acted linearly on respiratory motoneuron activity, but they were not independent.

Anaerobic metabolism during pubertal development at high altitude.

In a previous study we showed that there were no differences in anaerobic metabolism between groups of 11-yr-old children living at high (3,700 m) and low (330 m) altitudes. The aim of this study is to investigate changes in this metabolism during pubertal development. We compare blood lactate concentration ([L]) after maximal bicycle exercise in 20 boys acclimatized to high altitude (HA, 12 yr old) and at low altitude in 14 boys (LA1, 12 yr old) and in 13 boys (LA2, 14 yr old). The subjects had the same level of physical fitness and the same nutritional and socioeconomic status. Pubertal development was identified by salivary testosterone concentration ([T]). Results (means +/- SE) showed 1) at the age of 12 years, [L] and [T] in HA were significantly higher than in LA1 ([L] was 9.2 +/- 0.5 vs. 6.8 +/- 0.5 mmol/l, [T] was 233 +/- 66 vs. 132 +/- 30 pmol/l), 2) [L] and [T] in HA were statistically the same as in LA2, and 3) a linear relationship between [L] and [T] was significant (P less than 0.05) in all HA and LA subjects. This suggests that the higher [L] in 12-yr-old boys living at HA could result in an enhanced anaerobic metabolism linked to an earlier gonadal maturation evaluated by testosterone level.

Force-velocity and 30-s Wingate tests in boys at high and low altitudes.

The effects of high altitude (HA, 3,700 m) on performance during a force-velocity test (maximal anaerobic power, MAnP) and a 30-s Wingate test (mean power, P) were studied in boys 7-15 yr of age. Forty-seven children acclimatized to HA were compared with 101 living at low altitude (LA, 330 m). They had the same good nutritional status and the same level of physical activities [average 5.4 +/- 1.1 (SD) and 5.2 +/- 1.9 h/wk at HA and LA, respectively]. They performed the two tests using the same calibrated cycle ergometer. For the Wingate test, O2 uptake (VO2) during the 30 s and the peak of blood lactate concentration ([L]p) during the recovery were also measured. No difference in MAnP was observed between HA and LA. P, [L]p, and VO2 were lower at HA. This suggests that the altitude of 3,700 m did not affect the performance of the force-velocity test but reduced that of the Wingate test. This decrease in P was linked to a lower participation of glycolysis and aerobic metabolism. The latter is related to a reduced aerobic performance at HA. In addition, the slopes of the relationships between age and MAnP, P, and [L]p were the same at HA and LA, indicating that chronic hypoxia did not alter the development of the anaerobic metabolism during puberty.

Heart rate recording method validated by whole body indirect calorimetry in 10-yr-old children.

The aim of the study was to validate the heart rate (HR) recording method against whole body indirect calorimetry in prepubertal children. Nineteen 10.5-yr-old healthy children (10 boys, 9 girls) participated in this study. HR and energy expenditure (EE) were recorded through laboratory tests. Individual relationships between HR and EE were computed (equation established in laboratory). Several models were tested and validated from 24-h measurements of EE and HR by whole body indirect calorimetry. The best fit was obtained with individual polynomial relationships. Mean differences between predicted (equation established in laboratory) and measured total daily EE averaged 7.6 +/- 20.1%. The causes of the differences and the means of improving the accuracy of the prediction equation are discussed.

Oxygen debt in submaximal and supramaximal exercise in children at high and low altitude.

The effect of high altitude (HA) on O2 debt and blood lactate concentration [( L]) was examined in 10- to 13-yr-old children who exhibited the same level of physical fitness. Fifty-one children acclimatized to HA (3,700 m) were compared with 40 children living at low altitude (LA, 330 m) during submaximal (20-95% maximal aerobic power, MAP), maximal and supramaximal (115% MAP) bicycle exercise. Results showed that 1) maximal O2 uptake (VO2max) and maximal heart rate were significantly (P less than 0.001) lower at HA than at LA by 15% and 11 beats X min-1, respectively; 2) for a given absolute work load, O2 debt was higher at HA than at LA, and the slopes of the linear relationships between O2 debt and O2 uptake were significantly higher at HA; 3) when related to percent of VO2max, O2 debts in HA and LA were similar; for 115% MAP maximal O2 debt and [L] were not significantly different (maximal O2 debt, 45.7 +/- 2.7 and 45.9 +/- 3.8 ml X kg-1; [L], 6.0 +/- 0.3 and 6.7 +/- 0.5 mM); and 4) linear relationships between maximal O2 debt and [L] were the same at HA and LA. This suggests that HA did not modify the anaerobic capacity in children.

Effect of chronic hypoxia and socioeconomic status on VO2max and anaerobic power of Bolivian boys.

The aim of this work was to analyze the effects of altitude and socioeconomic and nutritional status on maximal oxygen uptake (VO2max) and anaerobic power (P) in 11-yr-old Bolivian boys. At both high (HA) (3,600 m) and low (LA) (420 m) altitudes, the boys were divided into high (HA1, n = 23, LA1, n = 48) and low (HA2, n = 44, LA2, n = 30) socioeconomic levels. Anthropometric characteristics, VO2max, and P [maximal P (Pmax) during a force-velocity test and mean P (P) during a 30-s Wingate test] were measured. Results showed that 1) anthropometric parameters were not different between HA1 and LA1 and HA2 and LA2 boys, but HA2 and LA2 boys were two years behind HA1 and LA1 boys in development; 2) VO2max was not different in boys from the same altitude, but at HA VO2max was 10% lower than at LA (HA1 = 37.2 +/- 5.6, HA2 = 38.9 +/- 6.4, LA1 = 42.5 +/- 5.8, LA2 = 42.5 +/- 5.3 ml.min-1 x kg-1 body wt); and 3) Pmax and P were higher in well-nourished than in undernourished boys, but there was no difference in Pmax and P between HA1 and LA1 and HA2 and LA2 boys (HA1 = 6.8 +/- 1.0, HA2 = 5.5 +/- 0.8, LA1 = 7.1 +/- 1.0, LA2 = 5.3 +/- 0.9 W/kg for Pmax; HA1 = 5.2 +/- 0.8, HA2 = 4.5 +/- 0.9, LA1 = 5.2 +/- 0.7, LA2 = 4.0 +/- 0.6 W/kg for P).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of altitude and socioeconomic status on VO2max and anaerobic power in prepubertal Bolivian girls.

The aim of this work was to evaluate the effects of high altitude and low socioeconomic status (SES) on aerobic and anaerobic power in 11-yr-old Bolivian girls. At both high (3,600 m) and low (420 m) altitudes, low-SES groups of girls were compared to similarly aged, high-SES girls. At low altitude, low-SES girls were also compared with younger high-SES girls with the same anthropometric characteristics. Anthropometric data were similar between high-SES and low-SES girls at both altitudes, but low-SES girls showed a 9-mo growth delay. Maximal O2 uptake was significantly lower for low-SES girls at both altitudes. Values did not differ when expressed relative to body weight at high altitude for high-SES vs. low-SES girls (37.6 +/- 1.2 vs. 39.3 +/- 1.0 ml.min-1.kg body wt-1), but a difference persisted at low altitude between high- and low-SES girls (37.5 +/- 1.0 vs. 34.7 +/- 0.7 ml.min-1.kg body wt-1). Anaerobic power (Pmax, force-velocity test; Pwing, Wingate test) was reduced for low-SES girls at both altitudes, whatever the mode of expression. For a given SES, the relative anaerobic performances were lower at low altitude. At low altitude, low-SES girls developed lower anaerobic power than did younger high-SES girls with similar anthropometric characteristics. In conclusion, at both altitudes, the reduction of anaerobic performances observed in girls of low SES could not be totally explained by anthropometric factors. Structural and/or functional muscle alterations are suggested. Moreover, at low altitude, tropical and other factors may have contributed to differences in performance between low- and high-SES girls.

Prediction of hypoxemia and mechanical ventilation after lung resection for cancer.

BACKGROUND: Hypoxemia usually occurs after thoracotomy, and respiratory failure represents a major complication. METHODS: To define predictive factors of postoperative hypoxemia and mechanical ventilation (MV), we prospectively studied 48 patients who had undergone lung resection. Preoperative data included, age, lung volume, force expiratory volume in one second (FEV1), predictive postoperative FEV1 (FEV1ppo), blood gases, diffusing capacity, and number of resected subsegments. RESULTS: On postoperative day 1 or 2, hypoxemia was assessed by measurement of PaO2 and alveolar-arterial oxygen tension difference (A-aDO2) in 35 nonventilated patients breathing room air. The other patients (5 lobectomies, 9 pneumonectomies) required MV for pulmonary or nonpulmonary complications. Using simple and multiple regression analysis, the best predictors of postoperative hypoxemia were FEV1ppo (r = 0.74, p < 0.001) in lobectomy and tidal volume (r = 0.67, p < 0.01) in pneumonectomy. Using discriminant analysis, FEV1ppo in lobectomy and tidal volume in pneumonectomy were also considered as the best predictive factors of MV for pulmonary complications. CONCLUSIONS: These results suggest that the degree of chronic obstructive pulmonary disease in lobectomy and impairment of preoperative breathing pattern in pneumonectomy are the main factors of respiratory failure after lung resection.

Basal production of pentane in expired gas from healthy humans.

BACKGROUND: Pentane in exhaled gas is often used as an index of lipoperoxidation, but today, there is no standardization for its measurement. In this study, with our technical experience, we determined basal production of pentane in healthy subjects, and we evaluated variability of pentane flow 1 month later. METHODS: 18 subjects inhaled hydrocarbon-free air (HCFA) in order to realize a lung washout. Ambient air and three samples (at T0, T10, T30 min) of expired gas were concentrated using a "trap-and-purge" procedure. For the analysis of pentane, an Al(2)O(3)/KCl plot column contained in a gas chromatograph equipped with a flame ionization detector was used. RESULTS: After 10 min of washout, mean (+/-SD) exhalation rate of pentane was 1+/-0.6 pmol min(-1) kg(-1). After 30 min of washout, mean (+/-SD) exhalation rate of pentane was 0.7+/-0.5 pmol min(-1) kg(-1). No significant difference in pentane flow was shown 1 month later for eight subjects who repeated the protocol. CONCLUSION: With our results and data of the literature, exhalation rates of pentane from healthy adults appear to range between 0.3 and 2 pmol min(-1) kg(-1). The variability of pentane flow 1 month later seems not very important.

Increased resting energy expenditure is related to plasma TNF-alpha concentration in stable COPD patients.

UNLABELLED: The objective of this study was to test whether increased resting energy expenditure (REE) in chronic obstructive pulmonary disease (COPD) patients is related to increased cost of breathing and/or to increased cytokine production. In 36 non-inflammatory (CRP: 17.6 +/- 13.1 mg.l(-1), mean +/- SD; orosomucoid: 0.71 +/- 0.18 g.l(-1)), non-malnourished (BMI: 23.6 +/- 4.3 kg.m(-2)), clinically stable, non severely hypoxic COPD patients (60.5 +/- 8.9 years) we measured REE, pulmonary function and plasma cytokine concentrations (TNF-alpha, IL1 and IL6). REE was increased by 10 +/- 11% (P< 0.001) above predicted values. Plasma TNF-alpha concentration was increased in all patients (mean value 26.3 +/- 14.3 pg.ml(-1)). Excess REE (with respect to values predicted by Harris-Benedict equations) was correlated with plasma TNF-alpha concentration (P< 0.005), but not with the degree of airway obstruction, lung overinflation, or with oxygen cost of breathing. Theophylline treatment resulted in a significant increase in REE by 15%. IN CONCLUSION: non-malnourished, clinically stable, non-severely hypoxic COPD patients display an increased REE that is related with plasma TNF-alpha concentration (without apparent systemic inflammation) and to theophylline treatment, but that is independent of parameters of respiratory function.

Testing peak cycling performance: effects of braking force during growth.

The purpose of this study was to investigate the relationship between cycling peak power (CPP; flywheel inertia included) and the applied braking force (F(B)) on a friction-loaded cycle ergometer in male children, adolescents, and adults. A total of 520 male subjects aged 8-20 yr performed three brief maximal sprints against three F(B): 0.245, 0.491, and 0.736 N x kg(-1) body mass (BM) (corresponding applied loads: 25 [F(B)25], 50 [F(B)50], and 75 [F(B)75] g x kg(-1) BM). For each F(B), peak power (PP) was measured (PP25, PP50 and PP75). For each subject, the highest PP was defined as CPP. Results showed that PP was dependent on F(B). In young adults PP25 underestimated CPP by more than 10%, and consequently, F(B)25 seemed to be too low for this population. However, in children, PP75 underestimated CPP by about 20%. A F(B) of 0.736 N x kg(-1) BM was definitively too high for the pediatric population. Therefore, the optimal F(B), even corrected for BM, was lower in children than in adults. The influence of growth and maturation on the force-generating capacity of the leg muscles may explain this difference. In this study, however, it was shown that the difference between PP50 and CPP was independent of age for the whole population investigated. Consequently, when flywheel inertia is included, one cycling sprint with a F(B) of 0.495 N x kg(-1) BM (corresponding applied load: 50 g x kg(-1) BM) is a feasible method for testing both children, adolescents, or young adults.

Oxygen toxicity: simultaneous measure of pentane and malondialdehyde in humans exposed to hyperoxia.

In order to estimate cell damage caused by free radicals during oxygenotherapy, we investigated the time course of two markers of lipoperoxidation: pentane in breath and malondialdehyde (MDA) in blood during brief normobaric hyperoxia. Nine healthy subjects inhaled hydrocarbon-free air (HCFA) for 30 minutes, hydrocarbon-free 100% O2 (HCFO2) for 125 minutes and then HCFA for 70 minutes. After 15 minutes of washout with HCFA, ambient pentane was eliminated. After HCFO2, at T175 versus T30 (i.e., 145 min from the start of 100% HCFO2), pentane production increased (P< 0.05). MDA rose significantly at T155 min (i.e., 125 min from the start of HCFO2), versus T30 (P< 0.01). These results suggest that acute hyperoxia causes a moderate increase in lipid peroxidation in healthy subjects. The increase of pentane and MDA confirms that acute hyperoxia induces lipid peroxidation in healthy subjects.

Vasomotor effects of transcutaneous CO2 in stage II peripheral occlusive arterial disease.

Vasomotor effects of skin exposure to carbon dioxide (CO2) have been described in normal subjects. It was of interest, therefore, to determine whether percutaneous CO2 is of therapeutic benefit. In a randomized, double-blind study, 10 patients with lower limb arteriopathy (stage II) were investigated before and after local exposure for twenty minutes to CO2-rich spa gas or to water-vapor-saturated air at the same temperature as that CO2-rich spa gas. Brachial and femoral blood flows, brachial and posterior tibial artery pressures, heart rate, and chest and foot transcutaneous oxygen tensions (tcPO2) were determined. Femoral blood flow, tibial pressure, and foot tcPO2 were significantly increased after exposure of the skin to CO2-rich spa gas. This effect was not accompanied with systemic hemodynamic modifications. Water-vapor-saturated air had no effect. These results suggest that transfer of CO2 across the skin can have beneficial local vasomotor effects in patients with lower limb stage II arteriopathy.

Maximal aerobic velocity measured by the 5-min running field test on two different fitness level groups.

The aim of the study was to verify the validity and the accuracy of the 5-min running field test (5RFT) relatively to the classical treadmill test. Two groups of subjects were tested, the first one being made of sub-elite runners (G1, n = 18) and the second one of athletes of other individual or collective disciplines (G2, n = 23). To check the field technique, maximal aerobic velocity (vamax) and an approached VO2max calculated from vamax during the 5RFT were compared with the corresponding values directly determined during a treadmill test. vamax obtained on treadmill (vamax(t)) or during a 5RFT (vamax(5)) were significantly higher in G1 than in G2 (+3.7 km.h-1 and +3.6 km.h-1 among the test). In each group, the difference between vamax(t) and vamax(5) was not significant (19.4 +/- 1.0 vs 19.5 +/- 0.9 km.h-1 in G1; 15.7 +/- 2.2 vs 15.9 +/- 1.2 km.h-1 in G2). A significant correlation was found between vamax(t) and vamax(5) (slope = 0.92; r = 0.86 in G1; slope = 0.71; r = 0.84 in G2). In each group, the approached VO2max(5) was significantly higher than VO2max(t) (respectively 67.8 +/- 2.9 vs 63.7 +/- 3.5 in G1; 54.8 +/- 3.9 vs 52.0 +/- 3.2 ml.min-1.kg-1 in G2. Weak but significant correlations were found between VO2(t) and vamax(5) (r = 0.69 and r = 0.56 respectively in G1 and G2). In conclusion, the 5RFT allows to measure vamax accurately whatever the physical fitness of the subjects but more closely in runners than in non-runners. The low correlation between VO2max(t) and vamax(5) for both groups indicates that a vamax running field test is specific and cannot evaluate VO2max with reasonable accuracy whatever the group, runners or non-runners.

High-intensity intermittent activities at school: controversies and facts.

In comparison to continuous aerobic type activity, little is known about high-intensity intermittent physical activity in children. Repeated short-term high-intensity activities (> maximal aerobic speed and <10 s) are more characteristic of the spontaneous physical activity of children. Recent studies have shown during repetitive bouts of sprints separated by short recovery intervals, that prepubescent children compared with adults are more able to maintain their performance without substantial fatigue. Moreover, repetitive runs at high velocities (near and higher than the maximal aerobic speed) separated by short recovery periods may elicit a high oxygen consumption in children. Several studies using interval training programmes for 7 weeks, twice a week for 30 min in physical education lessons showed that children's aerobic performance (maximal O2 uptake, maximal aerobic speed) could be enhanced. Training based on these repeated short-term high-intensity exercises could also improve children's anaerobic performance (short-term muscle power, strength and speed). Current evidence suggests that recovery from high-intensity exercises is faster in children than in adults and that repeated runs at high velocities separated by short recovery intervals can improve both aerobic and anaerobic performance. Although continuous aerobic type activity is more scientifically established as a training mode, repeated short-term high-intensity exercises in physical education programmes should be considered to enhance aerobic, as well as, anaerobic fitness in children.

Effect of air diving exposure generally encountered by recreational divers: oxidative stress?

Long term effects on respiratory function have been found in air divers and have indicated the development of small-airway disease. These effects have been attributed to oxygen toxicity or to venous gas micro emboli (VGM). The airway obstructions observed in air divers raise fundamental questions about whether these alterations exist after one simulated dive. The aim of this report was to study the oxidative stress induced by brief normobaric hyperoxia (FiO2 = 0.6 for 30 min) by measuring breath-exhaled compounds. Oxidative stress was measured by pentane in the expirate of 7 subjects ventilated with hydrocarbon-free air (HFA) before and after the hyperoxic exposure. NO concentration allowed us to determine the inflammatory response in the airway. Venous blood was drawn before and after the O2 breathing period for measurements of malondialdehyde (MDA). In all seven subjects, pentane elimination rates on 60%O2 do not increase after hyperoxia. NO rates during the HFA and hyperoxic exposures are significantly increased (p < 0.05). MDA concentrations are not changed after the hyperoxic exposure. Pulmonary function parameters obtained 225 minutes after hyperoxia are not changed. These results provide evidence that a dry gas and oxygen breathing (FiO2 = 0.6) for 30 min can raise exhaled NO. Oxidative stress assessed by pentane and MDA does not exist. We conclude that dry gas and the mild, 30 minute hyperoxic exposure, frequently encountered by recreational divers may be responsible for an airway inflammation. The consequences of such chronic exposure remains to be established.

[Long-term radiology and respiratory function study following exposure to asbestos]. / Etude radiologique et fonctionnelle respiratoire au long cours après exposition à l'amiante.

During the supervision of 93 workers in an asbestos factory pulmonary function tests and radiographs were performed using the same equipment and by the same team, at 5 yearly intervals. The assessment of radiographic changes was judged by following both the reader of the films and the technique used (either un-named films or simultaneous films at 5 yearly intervals). On reading un-named films the appraisal of parenchymal abnormalities was variable from one reader to another; on the other hand they were less marked for simultaneous readings made by the same observer. Progressive pulmonary function tests showed that the fall in vital capacity and of VEMS in 5 year intervals was more rapid when there was a parenchymal abnormality, when the duration of exposure was long or the subject was older when first exposed. The results showed that in spite of ceasing to be exposed the parenchymal abnormalities progressed.

[Analysis of nasal and exhaled nitric oxide concentration in nasal polyposis]. / Analyse des concentrations nasales et dans l'air expiré du monoxyde d'azote (NO) dans la polypose naso-sinusienne.

UNLABELLED: Nitric oxide (NO) is implicated in the pathophysiology of inflammatory airway diseases. It has been identified as a potential marker of airway inflammation. OBJECTIVE: The purpose of the study was to assess the concentrations of nasal NO in upper and lower airways in nasal polyposis patients. PATIENTS: 18 nasal polyposis patients (14 men, 4 women) and 21 control subjects (7 men, 14 women), all non asthmatic non smokers, without respiratory infections were prospectively studied. METHODS: They included nasal obstruction scoring, nasal endoscopic grading, allergy testing, nasal cytology, flow-volume spirometry and measurement of nasal (NNO) and exhaled NO (ENO) concentrations. NO was measured by a chemiluminescence NO Analyser (Sievers 280). NNO was analysed by aspiration with a constant flow of 3 l/mn. ENO was analysed during a slow expiration (50 ml/s) against a constant resistance of 10 cm H2O. RESULTS: NNO was significantly (p<0,001) decreased in NP group (596.4 +/- 102.06 ppb) compared to control group (2 251.6 +/- 288.6 ppb). ENO was significantly (p<0.05) increased in NP group (45.4 +/- 14.1 ppb) compared to control group (11.2 +/- 1.16 ppb). NNO and ENO were not significantly different between atopic and non-atopic NP patients. NNO concentrations was inversely correlated with the values of nasal endoscopic grading. No correlation was found between NNO concentrations and respectively nasal obstruction scoring and eosinophil count in nasal mucosa. CONCLUSION: Further studies are necessary to understand the pathophysiology of decreasing NNO and increasing ENO in nasal polyposis. In particular, ENO could be consider as a biologic marker of lower airway inflammation in nasal polyposis.