Structural Effects of Gas Hydrate Antiagglomerant Molecules on Interfacial Interparticle Force Interactions.

Gas hydrate interparticle cohesive forces are important to determine the hydrate crystal particle agglomeration behavior and subsequent hydrate slurry transport that is critical to preventing potentially catastrophic consequences of subsea oil/gas pipeline blockages. A unique high-pressure micromechanical force apparatus has been employed to investigate the effect of the molecular structure of industrially relevant hydrate antiagglomerant (AA) inhibitors on gas hydrate crystal interparticle interactions. Four AA molecules with known detailed structures [quaternary ammonium salts with two long tails (R1) and one short tail (R2)] in which the R1 has 12 carbon (C12) and 8 carbon (C8) and saturated (C-C) versus unsaturated (C═C) bonding are used in this work to investigate their interfacial activity to suppress hydrate crystal interparticle interactions in the presence of two liquid hydrocarbons (n-dodecane and n-heptane). All AAs were able to reduce the interparticle cohesive force from the baseline (23.5 ± 2.5 mN m-1), but AA-C12 shows superior performance in both liquid hydrocarbons compared to the other AAs. The interfacial measurements indicate that the AA with an R1 longer alkyl chain length can provide a denser barrier, and the AA molecules may have higher packing density when the AA R1 alkyl tail length is comparable to that of the liquid hydrocarbon chain on the gas hydrate crystal surface. Increasing the salinity can promote the effectiveness of an AA molecule and can also eliminate the effect of longer particle contact times, which typically increases the interparticle cohesive force. This work reports the first experimental investigation of high-performance known molecular structure AAs under industrially relevant conditions, showing that these molecules can reduce the interfacial tension and increase the gas hydrate-water contact angle, thereby minimizing the gas hydrate interparticle interactions. The structure-performance relation reported in this work can be used to help in the design of improved AA inhibitor molecules that will be critical to industrial hydrate crystal slurry transport.

The National Dose Registry-Canadian occupational exposure to ionising radiation, 1998-2018.

The National Dose Registry (NDR) is owned and operated independently by Health Canada. This paper provides an overview of how the registry operates within the Canadian regulatory structure, followed by an analysis of annual effective dose trends in nine job classes with relatively higher mean annual effective doses, i.e. greater than 1 mSv as reported in 2017. The analysis showed that, with a few exceptions, mean annual effective doses have generally decreased or remained practically unchanged in the past two decades at relatively low exposure levels. This review of occupational dose trends is evidence of the effectiveness of radiation protection programmes in Canada. The NDR has played an important role in the identification of relatively higher dose records and allowed the regulatory bodies to act immediately to ensure appropriate actions were taken.

A kit to facilitate and standardize the processing of sputum for measurement of airway inflammation.

BACKGROUND: The use of inflammometry has been shown to be effective for managing asthma. However, sputum processing can be time consuming. Furthermore, methods of sputum processing can vary among facilities. To help with standardization and to simplify the procedure for laboratory staff, a novel, commercially available processing device (Accufilter, Cellometrics Inc, Canada) has been developed. OBJECTIVE: To assess the validity of the Accufilter device and kit for recovery of treated specimens, and for quantitative sputum inflammatory cell counts by comparing intrasample measurements with those using the same procedure without the Accufilter device and kit. METHODS: The present study was a wet laboratory comparison of induced sputum cell counts obtained from sputum processed with versus without the device and kit. Comparisons of each sputum specimen were performed by the same technologist in random order. RESULTS: A total of 39 samples were processed using both the standard method and the Accufilter device. The intraclass correlation coefficients were high for the weight of the filtrate, and for eosinophil and neutrophil differential counts. CONCLUSION: A good degree of agreement of results was apparent when the two methods were compared. The differences noted between both methods were minimal and did not modify clinical interpretation. The use of the Accufilter device and kit can be used in place of the standard method for sputum quantitative analysis, especially in centres with large sample loads.

Work-exacerbated asthma and occupational asthma: do they really differ?

BACKGROUND: Although work-exacerbated asthma (WEA) is a prevalent condition likely to have an important societal burden, there are limited data on this condition. OBJECTIVES: The aims of this study were (1) to compare the clinical, functional, and inflammatory characteristics of workers with WEA and occupational asthma (OA) and (2) compare health care use and related costs between workers with WEA and OA, as well as between workers with work-related asthma (WRA; ie, WEA plus OA) and those with non-work-related asthma (NWRA) in a prospective study. METHODS: We performed a prospective observational study of workers with and without WRA with a 2-year follow-up. The diagnosis of OA and WEA was based on the positivity and negativity of results on specific inhalation challenges, respectively. RESULTS: One hundred fifty-four subjects were enrolled: 53 with WEA, 68 with OA, and 33 control asthmatic subjects (NWRA). WEA was associated with more frequent prescriptions of inhaled corticosteroids (odds ratio [OR], 4.4; 95% CI, 1.4-13.6; P = .009), a noneosinophilic phenotype (OR, 0.3; 95% CI, 0.1-0.9; P = .04), a trend toward a lower FEV1 (OR, 0.9; 95% CI, 0.9-1.0; P = .06), and a higher proportion of smokers (OR, 2.5; 95% CI, 0.96-9.7; P = .06) than the diagnosis of OA. The health care use of WRA and related costs were 10-fold higher than those of NWRA. CONCLUSION: Workers with WEA appeared to have features of greater asthma severity than workers with OA. In contrast with OA, WEA was associated with a noneosinophilic phenotype. Both OA and WEA were associated with greater health care use and 10-fold higher direct costs than NWRA.

Airway inflammatory responses following exposure to occupational agents.

BACKGROUND: Airway inflammatory responses to specific inhalation challenges (SICs) with low-molecular-weight (LMW) and high-molecular-weight (HMW) agents have not been studied thoroughly. We assessed the changes in airway inflammatory cells following SIC in sensitized workers, and looked at the influence of various factors on the pattern of inflammatory responses to SIC. METHODS: Induced sputum analysis was performed in workers sensitized to LMW (n = 41) or HMW agents (n = 41) after a control day and after a positive SIC. Cell counts were compared with lung function and various clinical parameters. RESULTS: In the LMW group, eosinophils were increased following late asthmatic responses (median [interquartile range], 0.02 [0.04] × 10(6) cells/g vs 0.30 [0.80] × 10(6) cells/g and 1.0% [3.5] vs 8.9% [8.0], P < .05), as were neutrophil numbers (0.8 [1.3] × 10(6) cells/g vs 2.3 [5.4] × 10(6) cells/g, P = .04). In the HMW group, eosinophil percentages increased both after early (1.0% [2.2] vs 5.5% [14.5], P = .003) and dual asthmatic responses (4.5% [3.7] vs 15.0% [13.7], P = .02). In the LMW group, the increases in neutrophils were higher in current smokers than in ex-smokers or nonsmokers. The length of exposure to the agent, tobacco use, and baseline percentage of eosinophils were independent predictors of the change in eosinophils, whereas age and baseline neutrophil percentage were predictors of the change in neutrophils. CONCLUSIONS: This study confirms that eosinophils and neutrophils are increased after SIC, whatever the causal agent. The type of agent is not predictive of the inflammatory response to SIC. Smoking is associated with a more neutrophilic response after SIC with an LMW agent.

Expiratory flows and airway inflammation in elderly asthmatic patients.

Asthma in the elderly is often underrecognized and suboptimally treated, resulting in an increased morbidity and mortality. The characteristics of asthma-related bronchitis and its optimal treatment remain to be determined in this population. We aimed to compare lung function and airway inflammation in elderly and younger asthmatic subjects. Data from two induced sputum databases were analyzed in three groups of asthmatic subjects (18-30 y, n = 136; 31-59 y, n = 385; 60-72 y, n = 172) and one group of healthy elderly subjects (60-89 y, n = 16). Expiratory flows and induced sputum cell counts were analyzed. Airway obstruction was more marked in elderly asthmatics compared with healthy elderly or younger asthmatic subjects (p < 0.01). An increase in sputum neutrophils and a decrease in macrophages and lymphocytes were observed in elderly asthmatics (p < 0.0001). Neutrophil percentages significantly increased with asthma severity in the young and the middle-aged groups, while they remained similar in elderly asthmatics regardless of asthma severity (p < 0.05). Neutrophil percentages weakly correlated with the dose of ICS in all asthmatics (r = 0.17, p < 0.0001). Age and dose of ICS were independent predictors of neutrophil percentage in asthmatic subjects in a regression model (R(2) = 0.12). Asthma in the elderly is associated with a more marked airway obstruction and sputum neutrophilia. Both age and the dose of corticosteroids need to be considered in the interpretation of the clinical relevance of sputum neutrophil count.

Comparative clinical and airway inflammatory features of asthmatics with or without polyps.

BACKGROUND: Nasal polyposis (NP) is associated with a more severe and steroid-resistant asthma. OBJECTIVE: To compare clinical and airway inflammatory features of asthmatics with or without NP. METHODS: Two groups of asthmatic patients were studied: group 1; n=39, with NP; group 2; n=40, without NP. Asthma control was assessed according to the Asthma Control Scoring System (ACSS). Expiratory flows, induced sputum, and blood eosinophils were also measured. RESULTS: ACSS score was lower (poorer control) in group 1 (meanA+-SEM = 73A+-3%) compared with group 2 (82A+-2%, p=0.01). FEV1 (mean of predicted value A+- SEM) was 81A+-3 for group 1 and 96A+-3 for group 2 (p=0.001), and the FEV1/FVC ratio was lower in group 1 (70A+-2%) compared with group 2 (76A+-1%, p=0.01). Blood and induced sputum eosinophils, as well as fibronectin and eosinophil cationic protein levels, were higher in group 1. CONCLUSION: Asthmatic subjects with NP have increased airway obstruction, increased inflammatory cells and reduced asthma control compared to those without NP. This may suggest a contribution of nasal polyps to the severity of asthma or a common susceptibility to develop upper and lower airways mucosal inflammation.

Benefits of low-dose inhaled fluticasone on airway response and inflammation in mild asthma.

RATIONALE: Current guidelines suggest that asthma should be controlled with the lowest dose of maintenance medication required. OBJECTIVES: To evaluate the effects of a low dose of inhaled corticosteroid compared to a placebo, on airway inflammation and responsiveness in patients with mild symptomatic asthma. METHODS: In this randomized double-blind, placebo-controlled, parallel group study, we looked at the influence of inhaled fluticasone propionate 250 microg/day for 3 months followed by 100 microg/day for 9 months on airway inflammation and methacholine responsiveness in non-smoking subjects with mild allergic asthma. Subjects were evaluated at baseline and 3, 6, 9 and 12 months after treatments; a 2-week evaluation of respiratory symptoms and peak expiratory flow measurements was done before each visit. RESULTS: Fifty-seven subjects completed the 3-month study period. Airway responsiveness, expressed as the PC20 methacholine, increased by 0.27 and 1.14 doubling concentrations, respectively, in placebo-treated (n=33) and in fluticasone-treated (n=24) asthmatic subjects (p=0.03). An additional improvement in PC20 up to 2.16 doubling concentrations was observed in the fluticasone-treated group during the 9-month lower-dose treatment (p=0.0004, end of low-dose period compared with placebo). Sputum eosinophil counts decreased after 3 months of fluticasone 250 microg/day compared with placebo (p<0.0001) and remained in the normal range during the 9-month lower-dose treatment. Respiratory symptoms and peak expiratory flows did not change significantly throughout the study in both groups. CONCLUSION: In mild asthma, keeping a regular minimal dose of ICS after asthma control has been achieved, may lead to a further reduction in airway responsiveness and keep sputum eosinophil count within the normal range.

Effects of protease inhibitors on mediator preservation in the supernatant of induced sputum.

Addition of protease inhibitors in induced sputum samples may help improve the recovery of mediators. The effect of protease inhibitors, in induced sputum, on the measurement of fibronectin, VEGF, IL-5, IL-6, and IL-8 was assessed. Protease inhibitors were added to sputum supernatant of atopic asthmatic subjects. Mediators were measured by ELISA or EIA. No differences were found in VEGF, IL-5, and IL-8 levels between protease inhibitors studied. Concentrations of IL-6 and fibronectin were higher when using, respectively, the commercial cocktail, and aprotinin. Protease inhibitors, if added, should be carefully chosen at the beginning of each study, to optimize the results.

A fast, simple, and inexpensive method to collect exhaled breath condensate for pH determination.

BACKGROUND: Exhaled breath condensate (EBC) analysis is a noninvasive method for assessing lower airway inflammation. Various methods of collecting EBC have been described. However, they are often time-consuming or involve expensive equipment. OBJECTIVE: To evaluate the efficiency and repeatability of a simple, fast, and inexpensive method of EBC collection for pH determination. METHODS: Twenty-four mild asthmatic patients, 18 moderate-to-severe asthmatic patients, and 26 controls were asked to slowly exhale for 45 seconds into a -80 degrees C cooled metal cylinder covered with protective rubber and attached to a piece of tubing. The EBC was collected using a syringe's plunger. The groups were compared regarding EBC pH. Reproducibility tests were also performed. Induced sputum samples were obtained for inflammatory cell counts. RESULTS: We obtained approximately 50 microL of EBC for pH determination. Mild asthmatic patients had lower mean +/- SD pH values than controls (5.97 +/- 0.48 vs 6.36 +/- 0.34; P = .008), and corticosteroid-treated, moderate-to-severe asthmatic patients had mean +/- SD pH values similar to controls (6.23 +/- 0.38; P > .05). Mean +/- SD sputum eosinophil percentages were higher in both asthmatic groups than in controls (3.42% +/- 5.37% and 4.14% +/- 4.98% vs 0.04% +/- 0.12%; P < .001) and were not correlated with pH values in all groups. The mean intraday coefficient of variation for the method was 4.8% (range, 0.9%-8.8%). No correlation was found in all groups between sputum neutrophils and pH. CONCLUSIONS: We developed a useful device for collecting EBC for pH evaluation that could provide an alternative to other methods when pH is the main variable evaluated.

Comparison of cell fixation methods of induced sputum specimens: an immunocytochemical analysis.

Induced sputum (IS) is a non-invasive method to evaluate airway inflammation. Various techniques are used to fix IS cells but their respective value has never been compared. We aimed to determine the best IS cell fixation technique for cellular markers staining. Cells were fixed using four methods: 1) periodate-paraformaldehyde-lysine (PLP)-sucrose, 2) paraformaldehyde 4% on slide and 3) in solution and 4) acetone-methanol. Analysis was based on percentage of positive cells compared to total cell counts stained by hematoxylin and quality of staining. Using PLP-sucrose resulted in a higher percentage of positive cells for CD3 and a better quality of staining. Acetone-methanol showed a lower percentage of positive cells for CD68 and a poor quality. PLP-sucrose gives the best results for the preservation of the studied cell markers and acetone-methanol the worst.

Clinical features and airway inflammation in mild asthma versus asymptomatic airway hyperresponsiveness.

RATIONALE: We still do not know why some subjects with airway hyperresponsiveness (AHR) experience no respiratory symptoms. OBJECTIVES: Our aim was to compare pulmonary function, perception of bronchoconstriction, and airway inflammation in atopic subjects with mild recently diagnosed (<5 years, n=30) or longer-standing (5 years or more, n=30) symptomatic asthma in comparison with atopic subjects with asymptomatic AHR (n=27). METHODS: All subjects had measurements of expiratory flows, PC(20) methacholine, perception of breathlessness and induced sputum cell differential, eosinophil cationic protein and alpha(2)-macroglobulin levels. RESULTS: Compared with the other groups, PC(20) was significantly lower in longer-standing asthma and perception score for breathlessness at 20% fall in FEV(1) was lower in asymptomatic subjects. Markers of airway inflammation were similar in all groups. There were no significant correlations between sputum eosinophils, alpha(2)-macroglobulin and/or eosinophil cationic protein levels and FEV(1), FVC or PC(20) in either group. CONCLUSION: Subjects with mild asthma or asymptomatic AHR are similar in regard to induced sputum markers of airway inflammation. Although perception of bronchoconstriction was slightly lower in asymptomatic subjects, additional factors are probably involved to explain why they report no respiratory symptoms. Further studies are needed to determine why these last are asymptomatic.

Optimization of the conditions for preservation of induced sputum: influence of freezing on cellular analysis.

BACKGROUND: Induced sputum (IS) analysis is a noninvasive, valid, and reproducible method for evaluating airway inflammation. It has been suggested that freezing of IS samples in order to delay analysis is feasible. However, the optimal conditions for preservation of IS samples have not been determined. OBJECTIVES: To determine optimal freezing conditions of IS samples, ensuring adequate specimen quality for assessment of cell viability, total cell count, and differential cell count. SUBJECTS AND METHODS: Twenty-one subjects were enrolled: 6 healthy control subjects, 5 patients with allergic rhinitis, 5 patients with mild asthma, and 5 patients with severe asthma. Each came to the laboratory once for IS sampling. Cell plugs were homogenized with dithiothreitol and separated into 12 aliquots. Viability and total and differential cell counts were determined for each aliquot. Bovine serum albumin (BSA) with dimethylsulfoxide (DMSO) was added to half of the aliquots, and fetal bovine serum (FBS) with DMSO was added to the other half. One half of the aliquots containing BSA or FBS were frozen at -20 degrees C, and the other half were frozen at - 80 degrees C. After 3, 7, or 10 days, samples were thawed and total cell counts, viability, and differential cell counts were assessed. RESULTS: Slide quality and total cell counts did not vary significantly according to freezing duration, temperature, or medium when compared to nonfrozen control samples. With FBS at -80 degrees C, cell viability did not vary significantly between control samples and freezing for 3, 7, and 10 days (59% vs 54%, 59% vs 54%, and 58% vs 54%, respectively; p > 0.05), whereas every other condition showed a significant decrease. Freezing did not affect the eosinophil percentage significantly. CONCLUSION: Freezing of IS samples in FBS with DMSO at - 80 degrees C allows adequate preservation of IS specimens. Samples can be kept for at least 10 days in those conditions without significantly altering total cell counts, viability, and eosinophil percentage.

Metalloproteinase-9 in induced sputum correlates with the severity of the late allergen-induced asthmatic response.

BACKGROUND: Asthma is characterized by airway inflammation and remodeling in which matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMP) play an important role. Allergen exposure activates the inflammatory/repair process in sensitized subjects. Induced-sputum analysis is a non-invasive method that allows the assessment of changes in inflammatory and remodeling mediators implicated in asthma. OBJECTIVES: To evaluate the changes in MMP-9 and its principal inhibitor (TIMP-1) in sputum and plasma of mild allergic asthmatic subjects after whole-lung allergen challenge. METHODS: Induced sputum and blood samples were obtained at baseline, and 6 and 24 h after challenge. MMP-9 and TIMP-1 levels in sputum and plasma were measured by ELISA. RESULTS: Allergen challenge increased the percentage of sputum eosinophils and MMP-9 levels 6 and 24 h after the challenge compared to baseline levels, but TIMP-1 levels did not vary significantly. A significant correlation was observed between MMP-9 levels at 6 h and the maximum percent fall in FEV(1) during the late response. Throughout the study, MMP-9 levels correlated significantly with the number of neutrophils in sputum. CONCLUSIONS: This study shows that analysis of induced sputum is a useful tool to study the variations in MMP-9 and TIMP-1 levels following allergen challenge, therefore allowing to evaluate their role in allergen-induced airway damage and repair.