Genotoxicity of aerosol extracts: Some methodological aspects and the contribution of urban and industrial locations

The genotoxicity of aerosol extracts was investigated with the Ames test and an SCE test in vitro. In addition to experiments to evaluate current techniques, a so-called gradient study was carried out in an industrialized part of The Netherlands to obtain insight into the contribution of urban and industrial locations to the genotoxicity of aerosol extracts. The influence of variations in the sampling was investigated. The results indicate that moderate variations in the volume of air sampled per unit of time and of the duration of the sampling period do not have a great influence on the effect measured.Experiments with filters impregnated with ¹⁴C-labelled benzo[a]pyrene showed that this compound is converted during sampling into directly active mutagens; no evaporation occurred. The results of experiments to evaluate the extraction procedure indicated that an 8-h Soxhlet extraction with methanol is better than, or as good as, Soxhlet extraction with other solvents.The gradient study showed that the aerosol downwind from industrial/urban areas exerted a reproducibly stronger effect in the Ames test and the SCE test when compared with aerosol from sea air.     

Genotoxicity of aerosol extracts. Some methodological aspects and the contribution of urban and industrial locations

The genotoxicity of aerosol extracts was investigated with the Ames test and an SCE test in vitro. In addition to experiments to evaluate current techniques, a so-called gradient study was carried out in an industrialized part of The Netherlands to obtain insight into the contribution of urban and industrial locations to the genotoxicity of aerosol extracts. The influence of variations in the sampling was investigated. The results indicate that moderate variations in the volume of air sampled per unit of time and of the duration of the sampling period do not have a great influence on the effect measured. Experiments with filters impregnated with 14C-labelled benzo[a]pyrene showed that this compound is converted during sampling into directly active mutagens; no evaporation occurred. The results of experiments to evaluate the extraction procedure indicated that an 8-h Soxhlet extraction with methanol is better than, or as good as, Soxhlet extraction with other solvents. The gradient study showed that the aerosol downwind from industrial/urban areas exerted a reproducibly stronger effect in the Ames test and the SCE test when compared with aerosol from sea air.     

Field evidences for the positive effects of aerosols on tree growth

Theoretical and eddy covariance studies demonstrate that aerosol‐loading stimulates canopy photosynthesis, but field evidence for the aerosol effect on tree growth is limited. Here, we measured in situ daily stem growth rates of aspen trees under a wide range of aerosol‐loading in China. The results showed that daily stem growth rates were positively correlated with aerosol‐loading, even at exceptionally high aerosol levels. Using structural equation modeling analysis, we showed that variations in stem growth rates can be largely attributed to two environmental variables covarying with aerosol loading: diffuse fraction of radiation and vapor pressure deficit (VPD). Furthermore, we found that these two factors influence stem growth by influencing photosynthesis from different parts of canopy. Using field observations and a mechanistic photosynthesis model, we demonstrate that photosynthetic rates of both sun and shade leaves increased under high aerosol‐loading conditions but for different reasons. For sun leaves, the photosynthetic increase was primarily attributed to the concurrent lower VPD; for shade leaves, the positive aerosol effect was tightly connected with increased diffuse light. Overall, our study provides the first field evidence of increased tree growth under high aerosol loading. We highlight the importance of understanding biophysical mechanisms of aerosol‐meteorology interactions, and incorporating the different pathways of aerosol effects into earth system models to improve the prediction of large‐scale aerosol impacts, and the associated vegetation‐mediated climate feedbacks.     

Effect of the site of microbial aerosol application on the pathogenesis and clinical picture of aerosol infection]

On the basis of experimental and clinical study of infections with the aerosol mechanism of infection there was revealed a relationship between the fractional-dispersive composition of the microbial aerosol, the porta of infection and the clinico-pathogenetic peculiarities of the course of the disease. On the example of tularemia, plague and other nosological forms it was demonstrated that coarse-dispersive aerosol caused development of oculo-bubonic and anginous-bubonic form of the disease, whereas the high-dispersive aerosol led to the appearance of primary pneumonia. In experimental aerosol infection with the causative agents in which the infection under natural conditions is not air-borne (botulism, American horse encephalo-myelitis, etc.) specific disease as a rule develops without any primary affection of the respiratory organs.     

沙丁胺醇雾化吸入辅助治疗小儿支气管哮喘急性发作的疗效观察

目的:观察沙丁胺醇雾化吸入辅助治疗小儿支气管哮喘急性发作的疗效。方法:将纳入研究的170例处于支气管哮喘急性发作期的患儿随机分为A组和B组,各85例。A组给予常规西医治疗,B组在常规治疗的基础上给予沙丁胺醇雾化吸入治疗。治疗1周后观察疗效,并复查肺功能。结果:B组总有效率90.59%显著优于A组总有效率69.41%,比较有显著性差异(x2=11.912P0.05);治疗后,B组各肺功能指标改善幅度明显优于A组,比较均有显著性差异(P0.05)。结论:沙丁胺醇雾化吸入辅助治疗可迅速缓解小儿哮喘急性发作,且有助于改善肺功能,临床效果满意。     

检测病毒气溶胶存活的方法学研究

以钝齿棒状杆菌噬菌体B271血清型为病毒等小颗粒生物粒子的模拟剂,建立了一种适合这类小颗粒生物粒子气溶胶存活研究的方法。本文从该噬菌体耐气溶胶化特性、气溶胶粒谱、用气溶胶示踪剂求算物理衰亡的方法和气溶胶采样回收技术等方面探讨了病毒气溶胶存活研究中的几个关键技术问题,为病毒气溶胶存活研究提供了参考。     

Aerosolized MMR vaccine: evaluating potential transmission of components to vaccine administrators and contacts of vaccinees

Although numerous operative and immunological advantages accompany aerosol immunization, potential vaccine virus transmission from the aerosol device to vaccine administrators or from aerosol vaccinees to their contacts requires further study. We conducted a clinical and serological follow-up study of vaccine administrators and matched classroom or household contacts of young adults who received the MMR vaccines by aerosol or injection. Differences in incidence of clinical adverse events between vaccinees and contacts were not statistically significant. No seroresponses to any components of MMR vaccine were noted among 25 matched contacts of persons receiving injected vaccines, and only one equivocal seroresponse was noted among 25 matched contacts of aerosol recipients. No seroresponses were observed in 3 persons who administered aerosol vaccine. The composite findings of this study provide additional evidence of the safety of this approach.     

Determining the basic characteristics of aerosols suitable for studies of deposition in the respiratory tract

Studies of aerosol particle deposition in the respiratory tract requires experimental inhalation of artificial model aerosols. The paper formulates some of the most important requirements for the properties of such aerosols. Several suitable fractions were prepared as part of a research project dealing with the use of microporous polymers for diagnostic purposes. 5 fractions of the polymer designated G-gel 60 with the particle size as stated by the manufacturer, ranging from 3 to 7 micron were evaluated using a 16-channel particle dispersity analyzer HIAC/ROYCO MT 3210 with the sensor 1200 and operated by a microprocessor, the equipment being coupled to an APPLE IIe computer. G-gel 60 particles introduced into the aerosol were characterized by the parameters CMAD, MMAD and sg both numerically and graphically. The measurement procedure was found to be very sensitive with respect to all fractions in evaluating the subtile differences between different lot numbers of the aerosol. G-gel 60 fractions characterized both numerically and graphically were compared with the known aerosols from paraffin oil and atmospheric air. The equipment MT 3210 enables prompt determination of the percentages of aerosol particles distribution by size class. The authors conclude that the procedure, both in its numerical and graphical versions, is particularly suitable for the diagnosis of aerosol particles deposition in the respiratory tract, offering a new application for HIAC/ROYCO in the field of medicine. In evaluating atmospheric aerosol in exhaled air, the number of particles was found to be below that in inhaled air, the difference being dependent on the choice of investigation methods. Percentual distribution of deposited particles following one minute ventilation proved to be at its maximum, as regards atmospheric aerosol, in the 0.30-0.50 micron range. The deposition curve was similar to already published curves, being characterized by an S-shaped pattern with maximum deposition in the greater size classes. An analysis of inhaled, exhaled and deposited aerosol suggested that deposited aerosol is more polydisperse and has particles of greater sizes than inhaled aerosol. Investigation of the effect of apnoe on deposition indicated that deposition increased as a function of apnoeic pause.     

Reflex responses to capsaicin: intravenous, aerosol, and intratracheal administration

Intravenous capsaicin elicits the "pulmonary chemoreflex" (apnea, bradycardia, and hypotension) presumably through the stimulation of "pulmonary C-fibers." The present study was designed to ascertain whether tracheobronchial C-fibers play a role in the above reflex response. We compared the effects of capsaicin injected intravenously, administered as an aerosol, and administered topically into the intrathoracic trachea in anesthetized dogs (n = 17) and rats (n = 17). We measured esophageal, subglottic, and arterial pressures together with abdominal muscle electromyogram. Changes in expiratory duration [(TE), measured as the ratio TEtest to TEcontrol, mean +/- SD] due to capsaicin were similar with all three routes of administration in both dogs (intravenous, 7.9 +/- 4.6; aerosol, 5.5 +/- 3.1; topically into intrathoracic trachea, 7.1 +/- 4.8) and rats (intravenous, 22.6 +/- 10.3; aerosol, 11.1 +/- 8.2; topically into intrathoracic trachea, 21.6 +/- 4.6). An increase in laryngeal resistance was a constant finding in the rat, but it was less frequent in the dog. Cardiovascular responses consisting of bradycardia and hypotension occurred with all three routes of administration but had longer delays than the respiratory responses. Capsaicin instillation into the extrathoracic trachea in dogs (n = 7) also induced qualitatively similar cardiorespiratory responses. We conclude that 1) capsaicin-sensitive receptors are accessible from both the pulmonary circulation and the airway lumen and 2) afferents, even in the extrapulmonary portion of the tracheobronchial tree, can play a role in the reflex responses to intraluminal capsaicin.     

Aerosol bolus dispersion and convective mixing in human and dog lungs and physical models.

The dispersion of aerosol boluses in the lung is a probe for convective mixing and has been proposed as a marker for abnormal lung function. To better understand the factors underlying this phenomenon, aerosol dispersion was compared in human subjects, dogs, and various physical models. In all systems, dispersion increased with the volumetric penetration of the aerosol bolus. The rate of this increase was 83% greater in humans compared with dogs. Dispersion in dogs was close to that in a packed bed with beads of 2.5 mm. Aerosol dispersion decreased with increasing flow rate in human subjects. An artificial larynx inserted into the straight tube caused a 33% increase in dispersion. In humans, aerosol dispersion was significantly correlated with forced expired flow between 25 and 75% of vital capacity. A 2-s pause between inspiration and expiration increased dispersion 23-58% in three isolated dog lungs but did not affect dispersion in the packed bed. The data suggest that lung geometry, flow rate, particle mobility, and the larynx all significantly affect aerosol dispersion by influencing the reversibility of aerosol transport between inspiration and expiration.     

Use of aerosols to measure in vivo volume-dependent changes in lung air space dimensions

Using measurements of aerosol recovery following a 5-s breath hold [NRC(5)] as indices of lung air space dimensions, we evaluated the in vivo changes in these dimensions associated with changes in lung volume (VL). In anesthetized dogs, single breaths of a 1.2-micron monodisperse aerosol were introduced into the respirator's cycle at a number of isovolume points on the inflation and deflation limb of the pressure-volume curve for the dog's lungs. At isovolume, NRC(5) measured off the inflation limb was slightly larger than NRC(5) measured off the deflation limb, implying a larger mean air space dimension for the air space configuration on the inflation vs. the deflation limb. Since a constant aerosol tidal volume (VT) was used for all VL in all dogs, the proportion of the lung filled with aerosol, VT/VL = Pn (where Pn is defined as an index of aerosol penetration into the lung periphery), varied along with VL. In all dogs, we found that, for NRC(5) measurements with Pn less than 0.33, NRC(5) steadily increased with increasing VL, which implies an increasing mean air space dimension as VL increases. However, when we account for the effect that changes in Pn with increasing VL have on NRC(5), we conclude that the observed increase in NRC(5) with VL is primarily due to decreases in Pn and not increases in the mean air space dimension as VL increases.(ABSTRACT TRUNCATED AT 250 WORDS)     

氧驱动雾化吸入治疗婴幼儿毛细支气管炎的疗效观察

目的探讨硫酸特布他林、布地奈德联合雾化吸入对婴幼儿毛细支气管炎的疗效。方法将142例患者随机分为试验组（72例）与对照组（70例）。对照组进行抗病毒吸氧、止咳化痰等常规治疗;试验组在常规治疗的基础上,加用雾化吸入硫酸特布他林、布地奈德雾化液,比较两组疗效。结果试验组的疗效明显优于对照组（P〈0.01）。结论硫酸特布他林雾化液、布地奈德混悬液吸入能较快地改善呼吸功能,有效改善毛细支气管炎患儿症状,值得在基层医院推广。     

Effect of dust and anthropogenic aerosols on columnar aerosol optical properties over Darjeeling (2200 m asl), eastern Himalayas, India

Background

The loading of atmospheric particulate matter (aerosol) in the eastern Himalaya is mainly regulated by the locally generated anthropogenic aerosols from the biomass burning and by the aerosols transported from the distance sources. These different types of aerosol loading not only affect the aerosol chemistry but also produce consequent signature on the radiative properties of aerosol.

Methodology/Principal Findings

An extensive study has been made to study the seasonal variations in aerosol components of fine and coarse mode aerosols and black carbon along with the simultaneous measurements of aerosol optical depth on clear sky days over Darjeeling, a high altitude station (2200 masl) at eastern Himalayas during the year 2008. We observed a heavy loading of fine mode dust component (Ca²⁺) during pre-monsoon (Apr – May) which was higher by 162% than its annual mean whereas during winter (Dec – Feb), the loading of anthropogenic aerosol components mainly from biomass burning (fine mode SO₄ ²⁻ and black carbon) were higher (76% for black carbon and 96% for fine mode SO₄ ²⁻) from their annual means. These high increases in dust aerosols during pre-monsoon and anthropogenic aerosols during winter enhanced the aerosol optical depth by 25 and 40%, respectively. We observed that for every 1% increase in anthropogenic aerosols, AOD increased by 0.55% during winter whereas for every 1% increase in dust aerosols, AOD increased by 0.46% during pre-monsoon.

Conclusion/Significance

The natural dust transport process (during pre-monsoon) plays as important a role in the radiation effects as the anthropogenic biomass burning (during winter) and their differential effects (rate of increase of the AOD with that of the aerosol concentration) are also very similar. This should be taken into account in proper modeling of the atmospheric environment over eastern Himalayas.     

人体上呼吸道口喉呼吸流涡结构演化对病毒气溶胶扩散的影响研究

揭示涡结构演化对病毒气溶胶扩散的影响作用,对于有效防治呼吸道疾病具有非常重要的意义.本文运用大涡模拟的方法,对人体在循环呼吸模式下口喉模型内的涡结构演化及气溶胶扩散进行了数值仿真研究,分析了口喉模型内涡结构演化过程以及气溶胶扩散状态.结果表明：受呼吸流涡结构演化的影响,颗粒轨迹主要分布在上气道内涡量集中的区域;受横向涡结构和纵向涡结构的共同影响,部分病毒气溶胶颗粒具备了混合有环状轨迹和波状轨迹的螺旋状轨迹.本研究从微观角度揭示了涡结构演化与气溶胶扩散行为的关系,为深入认识病毒气溶胶上呼吸道传播特点提供了新的途径.     

Aerosol Inoculator for Exposure of Human Volunteers

The performance of an aerosol inoculator for human volunteers is described in tests that used the PR8 strain of type A influenza virus and sodium fluorescein as a physical tracer. Virus recovery from the aerosols was approximately 1% and was unaffected by such variables as prolonged aerosolization, total airflow, relative humidity, or method of sampling. The recovery of sodium fluorescein from the aerosol was approximately 12% and was influenced by total airflow rates and relative humidity. With this apparatus, it should be possible to deliver reasonably predictable and measurable doses of respiratory viruses to human subjects. The design makes it possible to dismantle the inoculator into its component parts to facilitate portability.     

The effect of arachidonic acid on airway responses of rhesus monkeys.

Rhesus monkeys with immediate-type airway responses to ascaris antigen were used to study the effect of arachidonic acid (Ar). Arachidonic acid produced no changes in pulmonary function parameters when delivered by aerosol at varying doses. However, when Ar was aerosolized prior to aerosol antigen challenge this resulted in a selective increase in pulmonary resistance (PR). This effect in PR was variable with intravenous Ar. Indomethacin (I) by aerosol was evaluated to determine whether it would block the post Ar increase in PR. This could not be accomplished because both aerosolized and intravenous I had a similar effect on the PR following antigen challenge. These effects of Ar and I may be due to production of airway reactive prostaglandins, their precursers or substances such as slow reacting substance.     

Systemic pilocarpine increases deposition of and decreases responsiveness to inhaled carbachol in sheep.

The purpose of this study was to determine whether excessive airway secretions could serve as a barrier function against inhaled particulate matter. To increase airway secretions, six conscious sheep were treated with pilocarpine (0.8 mg/kg i.v.). Pilocarpine increased pulmonary resistance (RL) and total aerosol deposition within five breaths (AD5) as determined by the rebreathing of an inert monodisperse aerosol. When RL had returned to baseline, AD5 remained elevated [21 +/- 2% (SE), P < 0.05] and tracheal secretions were increased (237 +/- 77%, P < 0.05) above the values before pilocarpine administration. A carbachol aerosol dose-response curve was carried out at this time and compared with a control carbachol dose-response curve by calculating the dose of carbachol required to increase RL by 400% (PD400). Mean PD400 was increased postpilocarpine by 53 +/- 18 (P < 0.05) and 85 +/- 25% (P < 0.05) when normalized for increased aerosol deposition. Thus, pilocarpine decreased airway responsiveness to inhaled carbachol despite increasing aerosol deposition. The pilocarpine-induced airway hyporesponsiveness to inhaled carbachol is consistent with the hypothesis that excessive secretions have a protective role in the airways.     

Peculiarities of Lycopodium spores sampling from the ambient atmosphere: physical effects and problems of representativeness

The process of aspiration of monodisperse Lycopodium spores (d = 32 μm) from the weakly disturbed atmosphere and the calm air into aerosol samplers of various designs was experimentally investigated. Besides, some qualitative and quantitative characteristics of the interaction of spores with inner surfaces of sampling lines were studied, three experimental installations being employed.

Thin- and thick-walled cylindrical probes, their inner diameters being 0.3–1.5 cm and their length being 10–50 cm, as well as probes of other geometries were used in the experiments. The flow rate varied from 1 to 1000 cm³ s^?1; the mean wind speed value varied from 0 to 2 m s^?1.

Some regularities of sampling of air-spores were obtained. The aerosol concentration distortions caused by particle inertia and rebound as well as the wall loss effect were determined. The analysis is provided with a number of practical recommendations for sampling air spores into probes of aerosol measurement devices.     

Assessment of microbial parameters as indicators of viral contamination of aerosol from urban sewage treatment plants

In order to evaluate possible indicators of viral aerosol contamination in sewage treatment plants, a year-long study was carried out on the relationships between the presence of cytopathogenic viruses and the counts of total bacteria, faecal streptococci and somatic coliphages in samples collected at various distances from the aerosol source (aeration tank). The activated sludge plant studied proved to be a significant source of microbe-bearing aerosol with high levels of viral contamination. When the virus was found in sewage, it was also found in the air, at least in the sites closest to the aeration tank. With regard to the possibility of using the chosen parameters as markers of viral contamination, the total bacteria and faecal streptococci counts were generally positively correlated with viral presence, while coliphage counts yielded no analogous relationship.     

Evaluation of specific activity of artifical and natural radionuclides in the sink of aerosol matter into forest ecosystems

A new procedure is proposed for the investigation of atmospheric radioactivity in the surface air layer through evaluation of specific activity of artificial and natural radionuclides in the aerosol sink. Dry deposition of aerosol particles is described. The collection of aerosol is carried out using a passive sampler in which chemically inert fibrous and powdered materials are used as a sorption substrate. Analysis of experimental results characterizing the features of radionuclide distribution in the aerosol sink during their introduction into a coniferous tree stand is presented.