Exhaled nitric oxide predicts airway hyper-responsiveness to hypertonic saline in children that wheeze.

BACKGROUND: Exhaled nitric oxide (eNO) has shown good validity for the assessment of airway inflammation in asthmatic children. In large-scale epidemiological studies, this method would be preferred above airway challenge tests, because it is a quick and easy applicable tool. OBJECTIVE: In this study, we aimed to assess the discriminatory capacity of eNO, and prechallenge FEV1 for airway hyper-responsiveness (AHR) in 8-13-year old schoolchildren. MATERIALS AND METHODS: Parents completed the ISAAC questionnaire, and children were tested for atopy, AHR to hypertonic (4.5%) saline (HS), and eNO. Diagnostic value was assessed by the area under the receiver operating curves (ROC), and calculation of positive and negative predicted values at different cut-off points for eNO and prechallenge FEV1. RESULTS: Areas under the ROC-curves of AHR were 0.65 for eNO and 0.62 for FEV1. Values increased to 0.71 and respectively 0.75 for a combined occurrence of AHR and current wheeze. Highest sensitivity and specificity were obtained at a cut-off value of 43 ppb for eNO and 103% predicted for FEV1. At these cut-off values, the positive predictive values for the presence of AHR in symptomatic children were respectively 83% (eNO) and 33% (FEV1), and negative predictive values in asymptomatic children were, respectively, 90 (eNO) and 80% (FEV1). CONCLUSION: Exhaled nitric oxide is a valid screening tool for AHR to HS in children that present with current wheeze, and it outperforms FEV1 as a predictor of AHR.

Dose dependency of adjuvant activity of particulate matter from five European sites in three seasons in an ovalbumin-mouse model.

Various particulate matter (PM) samples were tested for their adjuvant potency in an animal model of allergy (ovalbumin) in the European Union study entitled Respiratory Allergy and Inflammation Due to Ambient Particles. Coarse and fine ambient particles were collected during spring, summer, and winter in Rome, Oslo, Lodz, Amsterdam, and De Zilk. De Zilk, at the Dutch seaside, has mainly westerly winds and served as a negative pollution control. EHC-93 (Ottawa dust) was used as a positive control. We studied the adjuvant potency of the particle antibody responses to ovalbumin and histopathological changes in the lung. After a sensitization phase by coexposure to EHC-93 and ovalbumin, the antibody response to ovalbumin and inflammatory responses in the lung were huge. There was more adjuvant activity in reaction to 9-mg/ml samples than to 3-mg/ml samples. A best-fit analysis of these samples shows that the ambient coarse and fine particles at these sites, in combination with allergens, have severe to mild adjuvant activity in the order Lodz, Rome, Oslo, and Amsterdam. A high dose of the fine fraction was more potent than a high dose of the coarse fraction, except at De Zilk, where the reverse was true. Spring and winter PM was more potent than summer PM. Depending on the site, either a water-soluble or a water-insoluble fraction was responsible for the adjuvant activity. A concentration of 3 mg/ml is effective for screening high-activity samples, as is a concentration of 9 mg/ml for screening low-activity samples in the ovalbumin-mouse model.

Adjuvant activity of ambient particulate matter of different sites, sizes, and seasons in a respiratory allergy mouse model.

In the framework of an EU project entitled, "Respiratory Allergy and Inflammation due to Ambient Particles (RAIAP)", various ambient particulate matter samples were tested for their adjuvant potency in an animal allergy model to ovalbumin. Coarse (2.5-10 microm) and fine (0.15-2.5 microm) particles were collected during the spring, summer, and winter in Rome, Oslo, Lodz, and Amsterdam. Coarse and fine particles were also collected near a seaside location in the Netherlands, where prevailing winds are westerly. These latter particles served as a control, with a minimum contribution by traffic. Ottawa dust (EHC-93) was used as a standard reference sample. Immunoglobulins (IgE, IgG1, and IgG2a), histopathological changes in the lung, cytokines, and the number of cells and their differentiation in lung lavages were used as effect parameters to study the adjuvant potency of these particles. The particles (3 mg/ml) were mixed with ovalbumin (0.4 mg/ml) and intranasally administered during the sensitization or the challenge phase. Intranasal administration of ovalbumin only induced very little antibody response, but introduced a minor inflammatory response in the lung or BAL during the sensitization and challenge phase. On the contrary, after coexposure to EHC-93 and ovalbumin, a major increase was found in immunoglobulin levels specific for ovalbumin, and a major inflammatory response in lung and BAL was induced. Coexposure to ovalbumin with 4 out of 12 collected PM samples (3 mg/ml) resulted in an increase of mainly IgE and IgG1. The histopathological changes consisted of a small to severe peribronchial and perivascular inflammatory response, a hypertrophy of bronchiolar mucous cells and an increase in eosinophils and neutrophils in the BAL. Statistical evaluation of the above-mentioned parameters showed associations with PMx (coarse and fine), site, season, season x PMx, season x site and (PMx) x site. In addition, adjuvant activity of the PMx can be ranked as Lodz > Rome = Amsterdam > Oslo. When the different seasons were compared for IgE, PM from winter was found more active compared to PM from spring and summer. Only for the histopathological lesions, statistically significant difference in effects was found between coarse and fine (coarse > fine). No associations were found between the endotoxin content and the biological effects parameters, although endotoxin was much more confined to the coarse fraction. In conclusion, PM, both coarse and fine, and from various geographic sites, was found to differ in adjuvant activity; furthermore, winter was found more active than spring and summer.

Adjuvant activity of ambient particulate matter in macrophage activity-suppressed, N-acetylcysteine-treated, iNOS- and IL-4-deficient mice.

In previous studies, we have shown strong adjuvant activity for Ottawa dust (EHC-93) after coexposure of the BALB/c mouse to EHC-93 and ovalbumin. Mice were intranasally sensitized at days 0 and 14 with 200 microg ovalbumin and 150 microg EHC-93, and challenged with ovalbumin at days 35, 38, and 41 with 200 microg ovalbumin. Mice were autopsied at day 42. This adjuvant activity was shown for the antibody response to ovalbumin (immunoglobulins E, G1, and G2a), histopathological lesions in the lung, cytokines, and the numbers of eosinophils in lung lavages. To study the mechanisms of this adjuvant activity, mice (BALB/cC.D2-Vil6) with natural-resistance-associated macrophage protein (Nramp1s), BALB/c mice pretreated with the antioxidant N-acetylcysteine (NAC), mice (B6.129P2-Nos2tmLau) deficient in inducible nitric oxide synthase (iNOS), and mice with interleukin-4 (IL-4) deficiency (BALB/cIl4< tm2Nnt) were coexposed to ovalbumin and EHC-93. Our studies have shown that the adjuvant activity induced after such coexposure does not change if the macrophage activation of the mice is disturbed or if the mice have been pretreated with N-acetylcysteine. In addition, the adjuvant activity does not develop through the pathway in which inducible nitric oxide synthase is involved. Because the histopathological lesions are statistically significant less in the IL-4 knockout strain in comparison with the wild type, we conclude that interleukin-4 might play an important role in the adjuvant activity caused by EHC-93.

Immune system parameters in children of Central and Eastern Europe: the CESAR study.

OBJECTIVE: of this paper is to compare observed values of immune parameters obtained in the CESAR study (The Central Europe Study of Air Pollution and Respiratory Health, funded by EC PHARE program) with ranges derived from other large population-based studies. STUDY DESIGN: Data were collected in healthy school children aged 9-11 years, in 6 countries: Bulgaria, the Czech Republic, Hungary, Poland, Romania and the Slovak Republic with the same standard approach in 1996. Random samples of 85 children per country, from 19 communities were selected from children having completed the health questionnaire, in total 495 children were analyzed. Lymphocyte subsets were determined by two-colour flow cytometric immunophenotyping using the lysed whole blood method (Becton-Dickinson). For determination of immunoglobulin concentration in sera nephelometric method (Behring Nephelometer system) was used. RESULTS: Medians, (5th-95th percentiles) of the lymphocyte subsets absolute count (x 10(9)/l) were as follows: CD19+ B cells 0.36 (0.13-0.66), total CD3+ T cells 1.74 (0.98-2.90), CD3+CD4+ helper-inducer T cells 0.95 (0.47-1.78), CD3+CD8+ suppressor/cytotoxic T cells 0.71 (0.38-1.22), CD3-CD16+56+ NK cells 0.36 (0.14-0.78), and for CD3+CD4+/CD3+CD8+ ratio 1.4 (0.8-2.4). Medians, (5th-95th percentiles) of percentages of lymphocyte subpopulations (%) were as follows: CD19+ B 13 (7-22), CD3+ T 70 (59-80), CD3+CD4+ T 38 (27-48), CD3+CD8+ T 28 (20-39), CD3-CD16+56+ NK cells 14 (6-27). Medians, (2.5th-97.5th percentiles) of the total immunoglobulin [g/l] were 11.7 (7.4-18.2) for IgG, 1.2 (0.5-2.5) for IgM, and 1.5 (0.5-3.4) for IgA. Based on the aspects of the size of the CESAR immune biomarker study and on the use of the standardized protocols we recommend to use the reference ranges on lymphocyte subsets and immunoglobulin in Europe as provided by this study.

Intratracheal instillation of cytoplasmic granules from Phleum pratense pollen induces IgE- and cell-mediated responses in the Brown Norway rat.

BACKGROUND: Release of cytoplasmic granules from grass pollen upon contact with water is thought to be an important source of airborne allergens. OBJECTIVES: To investigate the humoral and cellular responses to intratracheal instillation of Phleum pratense (timothy grass) pollen cytoplasmic granules (PCG) in the Brown Norway rat. METHODS: PCG were purified from timothy grass pollen by filtration through 5-microm-mesh filters. Rats were sensitized (day 0) and challenged (day 21) intratracheally with purified PCG suspended in saline (6 x 10(6) PCG/rat). Rats were then challenged 4 weeks later (1.5 x 10(6) PCG/rat). Blood samples, bronchial lymph nodes and lungs were collected from the rats 4 days after the second challenge. PCG-specific IgE and IgG1 levels and specificity were determined by ELISA and Western blotting. Pollen, pollen extract and PCG-induced proliferation of lymph node cells were monitored by [(3)H]-thymidine incorporation in a lymph node assay. Histopathological examination was carried out on the lungs. RESULTS: Specific IgE and IgG1 were present in the sera. Cultured lymph node cells proliferated in the presence of pollen, pollen extract and PCG. Western blots showed that all major pollen allergens are recognized by IgE and IgG1 from PCG-treated rats. Histopathological examination revealed features of a mild allergic reaction. CONCLUSIONS: In our rat model of allergy, purified timothy grass PCG instillation induced specific antibodies and lymph node cell responses, comparable to those obtained with intact pollen.

The prevalence of allergic sensitisation in immigrant children in The Netherlands.

BACKGROUND: Differences in the prevalence of allergic sensitisation have been reported in immigrant children living in the same urban environment. The purpose of this study is to investigate the prevalence of allergic sensitisation in school children of Dutch, Turkish and Moroccan origin. METHODS: The prevalence of sensitisation to aero-allergens was assessed using the skin prick test in a non-selected sample of 512 children (response rate 54%) living in the same inner city district of Utrecht. In addition, exhaled nitric oxide (FeNO) was determined. RESULTS: The prevalence of allergic sensitisation was dependent on the ethnic origin. As compared with Dutch children (19.1%), a higher prevalence of allergic sensitisation was observed in immigrant children for whom both parents were born in Turkey (23.6%, not significant) or Morocco (30.6%, p<0.05). The prevalence of allergic sensitisation in Dutch children was nearly 2 times lower than the reported prevalence in German children. In all sensitised children, the mean FeNO value was significantly (p<0.05) higher than in non-sensitised children, and the mean FeNO level was highest in Moroccan children sensitised to indoor allergens. CONCLUSION: In The Netherlands, immigrant children show a higher prevalence of allergic sensitisation as compared to Dutch children.

Phleum pratense pollen starch granules induce humoral and cell-mediated immune responses in a rat model of allergy.

BACKGROUND: Timothy grass (Phleum pratense) pollen allergens are an important cause of allergic symptoms. However, pollen grains are too large to penetrate the deeper airways. Grass pollen is known to release allergen-bearing starch granules (SG) upon contact with water. These granules can create an inhalable allergenic aerosol capable of triggering an early asthmatic response and are implicated in thunderstorm-associated asthma. OBJECTIVE: We studied the humoral (IgE) and bronchial lymph node cells reactivities to SG from timothy grass pollen in pollen-sensitized rats. METHODS: Brown-Norway rats were sensitized (day 0) and challenged (day 21) intratracheally with intact pollen and kept immunized by pollen intranasal instillation by 4 weeks intervals during 3 months. Blood and bronchial lymph nodes were collected 7 days after the last intranasal challenge. SG were purified from fresh timothy grass pollen using 5 microm mesh filters. To determine the humoral response (IgE) to SG, we developed an original ELISA inhibition test, based on competition between pollen allergens and purified SG. The cell-mediated response to SG in the bronchial lymph node cells was determined by measuring the uptake of [3H]thymidine in a proliferation assay. RESULTS: An antibody response to SG was induced, and purified SG were able to inhibit the IgE ELISA absorbance by 45%. Pollen extract and intact pollen gave inhibitions of 55% and 52%, respectively. A cell-mediated response was also found, as pollen extract, intact pollen and SG triggered proliferation of bronchial lymph node cells. CONCLUSIONS: It was confirmed that timothy grass pollen contains allergen-loaded SG, which are released upon contact with water. These granules were shown to be recognized by pollen-sensitized rats sera and to trigger lymph node cell proliferation in these rats. These data provide new arguments supporting the implication of grass pollen SG in allergic asthma.

Optimization of route of administration for coexposure to ovalbumin and particle matter to induce adjuvant activity in respiratory allergy in the mouse.

Epidemiological and experimental studies have not only shown that air pollution induces increased pulmonary morbidity, and mortality, but also that air pollution components may potentiate allergic responses. The respiratory allergy model to ovalbumin in the mouse has been shown a useful tool to characterize the adjuvant potency of air pollution components. However, the choice for the most effective route of administration for testing small amounts of air pollution component is hampered by the diversity of routes of administration used. To test the adjuvant activity of airborne particles (Ottawa dust EHC-93), we studied the optimal route of respiratory administration: intranasally (in) and aerosol (aero) in comparison with responses observed by intraperitoneal (ip) with diesel exhaust particles (DEP) as a positive control. Our results show that the combination of in/aero with ovalbumin caused almost similar immunoglobulin (Ig)E and inflammatory responses compared to the ip/aero. In/in application induced less responses for IgE, less inflammation in the lung, and less increased numbers of eosinophils in the bronchoalveolar lavage (BAL). This response increased dramatically when ovalbumin was coadministered with DEP. Subsequently, EHC-93, which is made up of airborne particles, was tested via the in/in route of administration. EHC-93 induced similar IgE responses, inflammation, and eosinophilic response in BAL compared to DEP. In addition, EHC-93 increased the airway responsiveness of the ovalbumin-sensitized mice measured in unrestrained condition and not in nonsensitized control mice. It is concluded that intranasal sensitization with intranasal challenge with airborne particles (EHC-93) is an effective route of administration to show potency of adjuvant activity of airborne particles.

Flow dependency and off-line measurement of exhaled NO in children.

Levels of exhaled nitric oxide (eNO) are flow-dependent, and the choice of an optimal flow rate for off-line and on-line eNO measurement has raised much debate. Recently, a flow rate of 50 ml/s was recommended, but children younger than 5-6 years are not capable of stabilizing their expiratory flow at low flow rates. The power of off-line eNO values to discriminate between normal and atopic children was therefore evaluated at different exhalation flow rates. At flow rates of both 8.3 ml/s and of 350 ml/s, children (8-12 years) sensitive to house dust mite have two-fold higher eNO values (p < 0.001) as compared with children lacking such a sensitivity. The power of eNO to discriminate between normal and atopic subjects was similar at the two flow rates (no difference in AUC of receiver operation curves, p = 0.89). All children from 4.5 to 5 years of age (n = 29) could perform a single off-line exhalation manoeuvre at high (>350 ml/s) but not at low (8.3 ml/s) flow rates. At high exhalation flow rate, eNO was 7.1 +/- 2.4 (mean +/- SD) median, 6.5 p.p.b. with a mean variation coefficient of 5.5%. Depending on their developmental level, about half of the younger children (35-46 months of age) could perform an off-line exhalation manoeuvre at high flow rate with good reproducibility (mean variation coefficient of 6.6%). It is concluded that an exhalation flow rate of 350 ml/s is feasible to determine off-line eNO-values in children from 3.5 years of age, and that this high flow rate does not compromise the power of eNO to detect allergic disease.

Adjuvant activity of various diesel exhaust and ambient particles in two allergic models.

In the framework of an EU study entitled "Respiratory Allergy and Inflammation Due to Ambient Particles" (RAIAP), various collected particulate matter samples were to be tested for their adjuvant potency in two animal models of allergy. A pollen allergy model in the Brown Norway (BN) rat and an ovalbumin model in the BALB/c mouse were used in this study to compare the discriminatory value of these two models and to evaluate them for later studies of collected RAIAP-samples. Two different sources of diesel exhaust particles (DEP I and DEP II ), a residual oil fly ash source (ROFA), and two sources of ambient particles (Ottawa dust, EHC-93, and road tunnel dust, RTD) were tested. Rats were sensitized intratracheally with Timothy grass pollen (Phleum pratense, 200 microl, 10 mg/ml) on d 0, challenged on d 21, and examined on d 25. Mice were sensitized intranasally at d 0 and 14, challenged intranasally at d 35, 38, and 41 (50 microl, 0.4 mg ovalbumin/ml), and examined at d 42. Particulate matter (PM) was administered either during the sensitization phase only or during the sensitization and challenge phases (for mice only) or during the challenge phase only. In the pollen model, only DEP I, but not DEP II, ROFA, EHC-93, and RTD, stimulated the immunoglobulin (Ig) E and IgG1 response in serum to pollen allergens. In addition to this adjuvant effect noted, no other biomarkers in lung or bronchoalveolar lavage (BAL) revealed adjuvant activity in the pollen model. In the BAL of BN rats exposed to a combination of pollen and PM, the percentages of eosinophilic granulocytes were decreased compared to the BAL of BN rats immunized with pollen only. In the ovalbumin model, the IgE levels in serum were increased in mice after coexposure to ovalbumin and PM (including DEPI, DEPII, ROFA, EHC-93, and RTD) in the sensitization phase but not after coexposure during the challenge phase only. The inflammatory response was greater in the lung, predominantly the influx of eosinophilic granulocytes, as was observed by both histopathological examination and BAL analysis. In addition, BAL levels of inflammatory interleukin (IL)-4 were increased. Based on the IgE antibody response to ovalbumin, the ovalbumin model ranked the adjuvant capacity of the particles in the following order: RTD > ROFA > EHC-93 > DEPI > DEPII. In conclusion, the ovalbumin model is a sensitive system to detect adjuvant activity of airborne particles, whereas the pollen-induced allergy model in rat was less sensitive.

Acute effect of air pollution on respiratory complaints, exhaled NO and biomarkers in nasal lavages of allergic children during the pollen season.

During 2 months of the pollen season, the acute and putative adjuvant effect of traffic-related air pollution on respiratory health was investigated in children sensitised to grass pollen or house dust mite (HDM). Respiratory complaints were objectified via measurement of exhaled NO and inflammatory mediators in nasal lavage (NAL). During the study children, skin prick negative (n = 31) or positive to grass pollen (n = 22), HDM (n = 34) or grass pollen + HDM (n = 32), kept a daily diary on respiratory symptoms, and NAL and exhaled air was sampled twice a week. The level of air pollutants and pollen was monitored continuously. Like children sensitised to HDM, those sensitised to pollen reported respiratory complaints (shortness of breath, itchy eyes or blocked nose) more frequently than non-sensitised children during (but not before) the pollen season; the respiratory complaints of sensitised children were independent of the pollen level. In addition, exposure to increased levels of PM(10) induces 'shortness of breath' in pollen- and HDM-sensitised children, whereas ozone induces a blocked nose in HDM-sensitised children. Combined exposure to PM(10) + pollen and O(3) + pollen induces a blocked nose in both HDM-sensitised children and children sensitised to pollen + HDM. Significant positive associations were found between eNO and the levels of NO(2), CO, PM(2.5) and pollen in both sensitised and non-sensitised children. At the start of the pollen season, the NAL concentration of eosinophils and ECP in pollen-sensitised children was increased compared to winter, but their levels were not further affected by increased exposure to pollen or air pollution. In conclusion, during the pollen season, sensitised children continuously report a high prevalence of respiratory complaints which coincides with increased levels of upper and lower airway inflammatory markers. No additional pro-inflammatory effect of air pollution was observed, which indicates that air pollution does not facilitate allergen-induced inflammatory responses.

Exhaled NO level and number of eosinophils in nasal lavage as markers of pollen-induced upper and lower airway inflammation in children sensitive to grass pollen.

OBJECTIVES: This study investigates the upper and lower inflammatory response induced by natural exposure to grass pollen in atopic and non-atopic children. METHODS: After children's atopic profile had been assessed, their nasal lavage fluid (NAL) and exhaled air was sampled once before and once during the pollen season. Level of nitric oxide (NO) was determined in exhaled air, and the following mediators were measured in NAL: ECP, IL-6, IL-8, albumin, uric acid, and urea. The number of eosinophils in NAL was determined after Giemsa staining. During the experiment ozone and pollen levels were measured continuously. RESULTS: During the pollen season the level of grass pollen was 95 pollen grains per cubic metre. At baseline, 8.0% and 5.4% of total cells in NAL of children sensitive to, respectively, house dust mite (HDM) and pollen + HDM were eosinophils, whereas virtually no eosinophils were observed in NAL of non-atopic children. In contrast to the non-atopic and HDM groups, in children sensitive only to grass pollen, grass pollen induced a threefold increase in the percentage of NAL eosinophils and a 2.5-fold increase in the NAL level of ECP ( P<0.05). In all groups, the NAL levels of albumin, uric acid, urea, IL-6 and IL-8 were not significantly increased by pollen exposure. At baseline, children sensitive to HDM showed significantly higher exhaled nitric oxide (eNO) values than non-atopic subjects and children sensitive only to pollen (79 to 141% increase). During pollen exposure eNO of children sensitive only to pollen increased from 35.8 to 64.5 ppb ( P<0.05), whereas no increase in eNO was observed in the other children. CONCLUSION: Pollen-sensitive children show a season-dependent upper and lower airway inflammatory response, resembling the continuous inflammation in HDM-sensitive children.

Relationship between exhaled NO, respiratory symptoms, lung function, bronchial hyperresponsiveness, and blood eosinophilia in school children.

BACKGROUND: Exhaled nitric oxide (eNO) may serve as a non-invasive marker of airway inflammation but its relationship with other commonly used measures has not been evaluated. METHODS: Levels of eNO in a sample of 450 children aged 7-12 years out of a total sample of 2504 school children living in different urban areas near motorways were determined. The aim of this cross-sectional study was to explore the relationship between eNO, impairment of lung function (PEF, FVC, FEV(1) and MMEF), bronchial hyperresponsiveness (BHR), and blood eosinophilia in children with and without atopy as assessed by skin prick testing. RESULTS: Regression analysis showed that wheezing and nasal discharge and conjunctivitis that had occurred during the previous 12 months were positively associated with eNO levels in atopic children (relative increase of 1.48 and 1.41, respectively; p<0.05) but not in non-atopic children. Similarly, BHR and the number of blood eosinophils per ml were positively associated with eNO levels in atopic children (relative increase of 1.55 and 2.29, respectively; p<0.05) but not in non-atopic children. The lung function indices PEF, FVC, FEV(1) and MMEF were not associated with eNO levels. CONCLUSIONS: In addition to conventional lung function tests and symptom questionnaires, eNO is a suitable measure of airway inflammation and its application may reinforce the power of epidemiological surveys on respiratory health.

The relationship between exhaled nitric oxide and allergic sensitization in a random sample of school children.

BACKGROUND: Exhaled nitric oxide (NO) has been proposed as novel a non-invasive marker of airway inflammation. OBJECTIVE: The level of exhaled NO was determined in a random sample of school children (7-12 years old) with the aim of investigating the relationship between exhaled NO and sensitization to common allergens. RESULTS: In the 450 children tested by skin prick tests (SPT), the prevalence of sensitization was 29.5% (overall), 21.9% (sensitization to indoor allergens), and 15.0% (sensitization to outdoor allergens). Regression analysis showed that levels of exhaled nitric oxide were closely associated with various measures of sensitization to aeroallergens. Sensitization to indoor allergens was associated with higher levels of exhaled NO (eNO) than sensitization to outdoor allergens when assessed by IgE but not when assessed by SPT. Children with reported wheeze in the past 12 months had much stronger associations between sensitization and eNO than children without wheeze. CONCLUSION: We conclude that allergic sensitization is strongly associated with increased levels of exhaled NO, especially in children with wheeze.

Long-term effect of fish oil diet on basal and stimulated plasma glucose and insulin levels in ob/ob mice.

In this study, the ob/ob mouse model was used to investigate epidemiological evidence linking fish intake to relative reduction in incidence of Type 2 diabetes mellitus and glucose. We have investigated, in comparison to low and high fat diets, the effect of a fish oil diet on basal and stimulated plasma glucose and insulin levels in male and female ob/ob mice. Mice were fed for 12 months with a saturated fat diet containing 25% lard, with a low fat diet containing 5% soybean oil, with a polyunsaturated fat diet containing 25% safflower seed oil (n-6) or with polyunsaturated fat diet containing 23% fish oil (n-3). Total body weight increased to approximately 100 g at the end of the experiment, with the highest increase in the order of lard > safflower oil > fish oil > soybean oil diet. Intercurrent deaths were found especially in the fish oil diet group. Compared to the other diet groups, plasma insulin levels of the fish oil diet group were significantly increased 3 months after the start of the diet and remained higher for another 3 months. Thereafter, the level declined to those of the other diet groups. Glucose-tolerance tests at 3, 6, 8 and 10 months showed a tendency of more efficient tissue glucose uptake in the fish oil group compared to the other groups, which was in accordance with a higher plasma insulin levels. At 12 months, microscopy revealed an increased severity of hepatic brown pigment accumulation and extramedullary haematopoiesis in the spleen of mice fed with fish oil. We conclude that fish oil diet in ob/ob mice reduced the body weight gain and increased the glucose-induced insulin secretion. Fish oil diet also increased intercurrent mortality. However, a consistent course of death could not be established using morphological parameters.

Association between exhaled nitric oxide, ambient air pollution and respiratory health in school children.

OBJECTIVES: The aim of the study was to investigate whether the level of exhaled nitric oxide (eNO) provides a more sensitive measure to assess adverse pulmonary effects of air pollution than conventional lung function indices. METHOD: The non-selected cohort studied consisted of 68 children (aged 10-11 years) living in an urban environment. For 7 weeks respiratory complaints were reported daily by these children in a diary, and lung function measures and eNO levels were determined in the children once a week on days with various level of air pollution. RESULTS: During the study the increase in the levels of the various air pollutants was positively associated with eNO (6% to 31% increase; P<0.05) but not with lung function measures. In contrast to the lung function measures, the prevalence of respiratory symptoms such as "sore throat", "runny nose", "having a cold", and "sick at home" were positively associated with the level of eNO measured in the following week. CONCLUSIONS: Though clinically very meaningful, functional pulmonary measures appear to be too course to detect relatively mild clinical symptoms in response to exposure to air pollution. In an epidemiological setting the increase in eNO may represent a more suitable measure to assess such adverse effects.

Traffic-related air pollution affects peak expiratory flow, exhaled nitric oxide, and inflammatory nasal markers.

The authors used a longitudinal observational design, with repeated measures, to study the association between traffic-related air pollutants (i.e., nitric oxide, nitrogen dioxide, carbon monoxide, and Black Smoke) and respiratory symptoms. Subjects (N = 82) attended an elementary school in either Utrecht (i.e., urban children) or Bilthoven (i.e., suburban children). These two geographic areas differed with respect to levels of Black Smoke (means = 53 microg/m3 and 18 microg/m3, respectively). Levels of nitric oxide, nitrogen dioxide, carbon monoxide, and Black Smoke were consistently higher in Utrecht than in Bilthoven (mean daily ratios were 8, 1.5, 1.8, and 2.7, respectively). The authors compared mean levels of short-term effects of the aforementioned air pollutants on suburban and urban children. Urban children had higher mean levels (p = .05) of interleukin-8 (32%), urea (39%), uric acid (26%), albumin (15%), and nitric oxide metabolites (21%) in nasal lavage than did suburban children. Peak expiratory flow, exhaled nitric oxide levels, and nasal markers were associated with levels of particulate matter with diameters less than or equal to 10 microm, Black Smoke, nitrogen dioxide, and nitric oxide. With respect to per-unit increases in air pollution, urban children had more increased peak expiratory flow, higher levels of exhaled nitric oxide, and more increased release of uric acid, urea, and nitric oxide metabolites than suburban children. In summary, urban children had increased levels of inflammatory nasal markers, and their responses were more pronounced than were the suburban children's responses to the same increments of air pollution.

Exhaled nitric oxide: a novel biomarker of adverse respiratory health effects in epidemiological studies.

The sampling of exhaled breath is a noninvasive procedure that can be performed easily in adults, children, and patients with respiratory disease. Several studies have demonstrated increased exhaled nitric oxide in patients with pulmonary disease, including asthma. In addition, exhaled nitric oxide may be an elegant tool for monitoring of environmental health effects of air pollution and the prevalence of atopy in epidemiological surveys. Recent literature about exhaled nitric oxide is presented in this article. Technical, physiological, and behavioral confounding factors of exhaled nitric oxide measurement are outlined.

A simple method to sample exhaled NO not contaminated by ambient NO from children and adults in epidemiological studies.

We previously showed that contamination of exhaled air by ambient NO could be avoided by 1 min of breathing and final inhalation of clean air (clean air procedure) prior to exhaled air sampling in balloons. This approach is, however, unsuitable for sampling large groups in epidemiological studies, because it is time consuming and laborious. We therefore discarded the initial part of exhaled air, which may contain ambient NO, in prebags of 250, 540, 775, 1000, and 2000 ml. The subsequent part of exhaled air was sampled in balloons and the NO content was measured. Inflation of a prebag of 500 ml to prevent ambient NO contamination proved to be effective only at low ambient NO levels (<20 ppb). Larger sizes of the prebag (1000 ml for adults and 775 ml for children) are, however, required so that contamination of the air sample at higher levels of ambient NO (up to 115 ppb) is excluded. Using different prebags of gradually increasing size, it was shown that the initial part of exhaled air (<500 ml) contained relatively high amounts of NO that gradually decreased, but attained a constant level in the subsequent air volumes. Using rather large prebags of 2000 and 1000 ml, respectively, in adults and children yielded exhaled NO levels even below those obtained the clean air procedure was applied in combination with a prebag of 540 ml. As this reduction also occurs at ambient NO levels of nearly zero, we suggest that this reduction was due to interference by the water vapor arising from the lowest part of the lungs. In conclusion, the use of a prebag to discard the initial volume of exhaled air ensures accurate measurement of exhaled endogenous NO in large-scale epidemiological studies not biased by ambient NO.