微生物气溶胶采集技术的特点及应用

微生物气溶胶是悬浮于空气中粒径差异显著的生物粒子。污水处理、垃圾填埋等污水和固体废弃物的处理过程会产生大量的微生物气溶胶。近年来,随着对微生物气溶胶的不断认识,对其产生、逸散以及危害环境和人体的研究越来越多。在过去的150年,研究者们研发了多种微生物气溶胶采集技术和仪器设备,每种采集技术各有特点和适用条件。本文阐述沉降法、惯性采样法和过滤法3种典型微生物气溶胶采集技术的特点和原理,分析各种采样设备的适用性,为微生物气溶胶的采集和研究提供参考。     

Linking the conventional and emerging detection techniques for ambient bioaerosols: a review

Bioaerosols are biologically originated particles present in the atmosphere that can be formed from any process involving biological materials. They comprise of both living and non-living components including organisms, dispersal methods of organisms, and excretions. Bioaerosols such as airborne bacteria, fungal spores, pollen, and others possess diverse characteristics and effects. A large gap exists in the scientific understanding of the overall physical characteristics and measurement of bioaerosols. Consequently, this review aims to devise an appropriate approach to generate more scientific knowledge of bioaerosols. In addition to comparisons and discussions about the various factors affecting bioaerosols, sampling, handling, and the application of various devised analytical techniques, this review offers insight into the current state of bioaerosol research. The review focuses on instrumental and methodical strategies to understand bioaerosol measurement. Numerous studies have investigated conventional methods, advanced methods, and real-time methods that can be applied for bioaerosol monitoring. Each method is different in terms of working principle, characteristics, sensitivity, and efficiency. For the first time, this review explains and compares different methods of conventional, offline, online, and real-time detection methods of bioaerosols based on their working principles, sensitivity, and efficiency on a single platform. This will provide a clear concept and better options for selecting the appropriate method based on the research proposal. Furthermore, recent advances are summarized, and future outlooks are emphasized for bioaerosol identification and categorization. This study also encourages developing affordable and standardized methods to avoid the inter-laboratory and sampling variability to obtain a better understanding and comparison of bioaerosol measurements worldwide. Nevertheless, this work can assist researchers in selecting appropriate methods for bioaerosol measurement and investigation.

     

Inhibitory effects of diesel exhaust components and flavonoids on 20α-hydroxysteroid dehydrogenase activity in mouse tissues

The inhibitory effects of diesel exhaust components and flavonoids on 20α-hydroxysteroid dehydrogenase (20α-HSD) activity were examined in cytosolic fractions from the liver, kidney and lung of male mice. 9,10-Phenanthrenequinone (9,10-PQ) and 1,2-naphthoquinone (1,2-NQ), which are contained in diesel exhaust particles (DEPs), potently inhibited 20α-HSD activity in liver cytosol. 9,10-PQ also inhibited the enzyme activity in lung cytosol. However, 20α-HSD activity in kidney cytosol was little inhibited by 9,10-PQ or 1,2-NQ. Flavonoids such as quercetin, fisetin and kaempferol exhibited high inhibitory potencies for 20α-HSD activity in liver cytosol, whereas these flavonoids were poor inhibitors for the enzyme activity in kidney cytosol. It is likely that several diesel exhaust components and flavonoids augment the signaling of progesterone in the liver cells, by potently inhibiting 20α-HSD activity in mouse liver cytosol. The possibility that there are distinct enzymes catalyzing 20α-HSD activity in the non-reproductive tissues of male mice is also discussed.     

Inhibitory effects of diesel exhaust components and flavonoids on 20alpha-hydroxysteroid dehydrogenase activity in mouse tissues

The inhibitory effects of diesel exhaust components and flavonoids on 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) activity were examined in cytosolic fractions from the liver, kidney and lung of male mice. 9,10-Phenanthrenequinone (9,10-PQ) and 1,2-naphthoquinone (1,2-NQ), which are contained in diesel exhaust particles (DEPs), potently inhibited 20alpha-HSD activity in liver cytosol. 9,10-PQ also inhibited the enzyme activity in lung cytosol. However, 20alpha-HSD activity in kidney cytosol was little inhibited by 9,10-PQ or 1,2-NQ. Flavonoids such as quercetin, fisetin and kaempferol exhibited high inhibitory potencies for 20alpha-HSD activity in liver cytosol, whereas these flavonoids were poor inhibitors for the enzyme activity in kidney cytosol. It is likely that several diesel exhaust components and flavonoids augment the signaling of progesterone in the liver cells, by potently inhibiting 20alpha-HSD activity in mouse liver cytosol. The possibility that there are distinct enzymes catalyzing 20alpha-HSD activity in the non-reproductive tissues of male mice is also discussed.     

Short-term dynamic patterns of bioaerosol generation and displacement in an indoor environment

The short-term dynamics and distribution of airborne biological and total particles have been assessed in a large university hallway by particle counting using laser particle counters and impaction air samplers. Particle numbers of four different size ranges were determined every 2 min over several hours. Bioaerosols (culturable bacteria and fungi determined as colony-forming units) were directly collected every 5 min on Petri dishes containing the appropriate growth medium. Results clearly show distinct short-term dynamics of particulate aerosols, of both biological and non-biological origin. These reproducible periodic patterns are closely related to periods when lectures are held in lecture rooms and the intermissions in between when students are present in the hallway. Peaks of airborne culturable bacteria were observed with a periodicity of 1 h. Bioaerosol concentrations follow synchronously the variation in the total number of particles. These highly reproducible temporal dynamics should be considered when monitoring indoor environments to determine air quality.     

Mutagenic nitroarenes,diesel emissions,particulate-induced mutations and cancer: an essay on cancer-causation by a moving target

Initial analyses of the lung tumors seen in rats exposed for their lifetime to elevated levels of the emissions of diesel engines suggested that they were due to powerful mutagens and carcinogens (PAHs, nitro PAHS) adsorbed onto the diesel particles. However, further studies showed that carcinogenicity occurred only under conditions that resulted in impaired lung clearance (‘overloading’) leading to inflammatory reactions and other pathologic sequelae. These observations together with the findings that carbon black, a model for diesel particles devoid of organic mutagens and carcinogens, also induced lung cancers under conditions of overloading led to the suggestion that the cancers resulted from a non-genotoxic mechanism. However, the further finding that inert particulate carcinogens devoid of organics, induced mutations has led to a re-evaluation of the role of mutations in lung carcinogenesis caused by particles and the relevance of the rat model to humans. This is especially timely as epidemiological studies suggest that humans may develop lung cancers following occupational exposure to diesel emissions by a mechanism unlikely to involve lung overloading. Finally, the recent recognition that environmental PM-10 (respiratory size particles) may be responsible for a significant portion of human morbidity and mortality, ensures that the health effect of diesel emissions will continue to receive scrutiny as they contribute to the PM-10 load.     

The reactions of 1.0 nanometre diameter plutonium-238 dioxide particles with rat lung fluid.

The reactions of 1.0 nm particles of plutonium-238 dioxide with rat lung fluid have been studied both in vivo and in vitro. In both cases two products have been identified, (i) plutonium-labelled pulmonary surfactant and (ii) a heterogeneous plutonium-labelled material isolated by column chromatography. The formation of plutonium-labelled pulmonary surfactant results in the rapid translocation of plutonium from lungs to blood and in a high urinary excretion relative to administered plutonium citrate.     

The ultrastructure of mouse lung: the alveolar macrophage

Free alveolar macrophages of normal mouse lung have been studied in the electron microscope. The tissue was obtained from several young adult white mice. One other animal was instilled intranasally with diluted India ink 1(1/2) hours prior to the removal of the lung. Thin sections of the osmium-fixed, methacrylate-embedded tissue were examined either in an RCA EMU 2 electron microscope or in a Siemens and Halske Elmiskop I b. A few thick sections obtained from the same embeddings were stained for iron. The normal alveolar macrophages, which are usually in contact with the alveolar epithelium, were found to contain a variety of inclusion bodies, along with the usual cytoplasmic components like mitochondria, endoplasmic reticulum, and Palade granules. Another typical component of the cytoplasm of these cells which appears as small ( approximately 6 mmicro) very dense granules of composite fine structure is interpreted as ferritin. It is assumed that this ferritin is formed from red blood cells ingested by the alveolar macrophages. The macrophages in the alveoli were found to phagocytize intranasally instilled India ink particles. Such cells, with engulfed India ink particles, were often of more rounded form and the particles were frequently seen lying inside membrane-bound vacuoles or vesicles of the cytoplasm. The membrane of a few vesicles containing India ink particles was seen as the invaginated portion of the cell plasma membrane, and in one instance these same vesicles were seemingly interconnected with a rough surfaced cisterna of the endoplasmic reticulum. The process of phagocytosis is recognized as related to the "normal" process of pinocytosis.     

The Ultrastructure of Mouse Lung: The Alveolar Macrophage

Free alveolar macrophages of normal mouse lung have been studied in the electron microscope. The tissue was obtained from several young adult white mice. One other animal was instilled intranasally with diluted India ink 1½ hours prior to the removal of the lung. Thin sections of the osmium-fixed, methacrylate-embedded tissue were examined either in an RCA EMU 2 electron microscope or in a Siemens and Halske Elmiskop I b. A few thick sections obtained from the same embeddings were stained for iron. The normal alveolar macrophages, which are usually in contact with the alveolar epithelium, were found to contain a variety of inclusion bodies, along with the usual cytoplasmic components like mitochondria, endoplasmic reticulum, and Palade granules. Another typical component of the cytoplasm of these cells which appears as small (~6 mµ) very dense granules of composite fine structure is interpreted as ferritin. It is assumed that this ferritin is formed from red blood cells ingested by the alveolar macrophages. The macrophages in the alveoli were found to phagocytize intranasally instilled India ink particles. Such cells, with engulfed India ink particles, were often of more rounded form and the particles were frequently seen lying inside membrane-bound vacuoles or vesicles of the cytoplasm. The membrane of a few vesicles containing India ink particles was seen as the invaginated portion of the cell plasma membrane, and in one instance these same vesicles were seemingly interconnected with a rough surfaced cisterna of the endoplasmic reticulum. The process of phagocytosis is recognized as related to the "normal" process of pinocytosis.     

Lung tumor induction in Syrian hamsters with internally deposited particulate Pu: A synthesis based on microscopic dose distribution

Syrian hamsters inhaled a monodisperse aerosol of 238PuO2 and were serially sacrificed to study the microscopic distribution of particles, tissue at risk and dose as a function of time after exposure. The distribution of dose and tissue at risk around single particles in lung and the changes in distribution of particles with time have been reported previously. In the present paper, these measurements are applied to the computation of tissue-at-risk and radiation-dose-rate distributions within the lungs of Syrian hamsters. Based on these results, airway epithelium is irradiated at the same levels as other lung tissue and does not require separate consideration on the basis of dose to tissue. Incorporation of the measured microscopic radiation dose distribution into existing dose-effect models allowed data on lung tumor induction in Syrian hamsters from several laboratories to be adequately described by a model fit to data from a single laboratory.     

A large photoreactive particle from Chromatium vinosum chromatophores

Large photoreactive particles from Chromatium vinosum are obtained pure and in high yield by using a mixture of detergents at high ionic strength to dissociate the chromatophore membrane. The particles contain all of the secondary electron acceptor of the chromatophores and about half of the cytochrome. Their content of ubiquinone is greatly enriched as compared with chromatophores. The individual particles have an estimated molecular weight of between 650 000 and 810 000.Gel electrophoresis of the preparation in sodium dodecylsulfate shows polypeptides with molecular weights of 50–45 000, 30 000, 27 000, 22 000 and 12 000. The 50–45 000 components are cytochromes. The 30 000, 27 000 and 22 000 components may be analogous to the triad of polypeptides present in Rhodopseudomonas spheroides reaction centers. The non-cytochrome components are partly soluble in chloroform/methanol.Aggregates of particles appear in these preparations. Electron microscopy of the aggregates demonstrates rectilinear lattices of isodiametric particles, 120 Å in diameter. These sheet-like structures are one unit thick and typically contain 9–16 members. They appear to arise by aggregation during isolation but are probably similar to native aggregates apparent within chromatophores after treatment with detergents at low salt concentration.     

Ultrastructural and biochemical studies on ribonucleoprotein particles from isolated nucleoli of thioacetamide-treated rat liver

The morphology of isolated nucleolar ribonucleoprotein particles from thioacetamide-treated rat livers was found to be very similar to those in situ. The sedimentation profiles of these nucleolar ribonucleoprotein particles in sucrose density gradients showed the presence of three components. The particles in these peaks were electron opaque spherical particles that were quite homogeneous in size (200–250 Å). The ultrastructure of these RNP particles from thioacetamide-treated livers is similar to that of both ribosomes and intranucleolar RNP particles inasmuch as at high magnifications a convoluted, linear strand of RNA was observed to be present in each of the particles.     

CFD simulation of aerosol delivery to a human lung via surface acoustic wave nebulization

Administration of drug in the form of particles through inhalation is generally preferable in the treatment of respiratory disorders. Conventional inhalation therapy devices such as inhalers and nebulizers, nevertheless, suffer from low delivery efficiencies, wherein only a small fraction of the inhaled drug reaches the lower respiratory tract. This is primarily because these devices are not able to produce a sufficiently fine drug mist that has aerodynamic diameters on the order of a few microns. This study employs computational fluid dynamics to investigate the transport and deposition of the drug particles produced by a new aerosolization technique driven by surface acoustic waves (SAWs) into an in silico lung model geometrically reconstructed using computed tomography scanning. The particles generated by the SAW are released in different locations in a spacer chamber attached to a lung model extending from the mouth to the 6th generation of the lung bronchial tree. An Eulerian approach is used to solve the Navier–Stokes equations that govern the airflow within the respiratory tract, and a Lagrangian approach is adopted to track the particles, which are assumed to be spherical and inert. Due to the complexity of the lung geometry, the airflow patterns vary as it penetrates deeper into the lung. High inertia particles tend to deposit at locations where the geometry experiences a significant reduction in cross section. Our findings, nevertheless, show that the injection location can influence the delivery efficiency: Injection points close to the spacer centerline result in deeper penetration into the lung. Additionally, we found that the ratio of drug particles entering the right lung is significantly higher than the left lung, independent of the injection location. This is in good agreement with this fact that the most of airflow enters to the right lobes.     

Ultrastructural localization of Helix pomatia lectin-binding sites in mouse lung elastic fibers

Helix pomatia (Snail) lectin complexed with colloidal gold (HPL-gold) recognized binding sites on elastic fibers in plastic embedded sections of lung tissue from mice of several ages. Deposition of the lectin-gold particles was examined by electron microscopy. Structures such as the elastic laminae of pulmonary vessels and elastic fibers throughout the lung was specifically and intensely decorated by the HPL-gold complex and easily visualized. The binding of the HPL-gold particles was primarily to sites on the amorphous component of elastin, to the virtual exclusion of the microfibrillar elastin elements, collagen fibers and other components of the extracellular matrix. In addition, moderate age differences in the binding of HPL-gold to elastin were apparent. These observations appear to be the first demonstration of the presence, in the amorphous component of elastin, of glycoconjugates that are specifically recognized by HPL and suggest a method by which the involvement of glycoconjugates in lung elastogenesis could be explored.     

Ultrastructure and Histochemistry of the Food Trapping Mucous Film in Benthic Filter-Feeders (Ascidians)

Transmission and scanning electron microscopy of food trapping filters or “mucous films” of several Ascidians reveal the same type of extensive net with elongate rectangular meshes. The ultrastructural appearance and mesh size varies only slightly within the group. Pore sizes from 0.2 to 0.5 μm in width and from 0.5 to 2.2 μm in length with a thickness of the filaments from 10 to 40 nm are probably representative for the nets under in vivo conditions. These observations corroborate earlier experimental results which indicate a remarkably high and constant efficiency of filtration in all species kept undisturbed. Great quantities of water are evidently filtered through these nets at relatively low resistance and particles even below bacterial size (0.5 μm) are effectively trapped. Histochemical reactions indicate the presence of both mucoproteins and acidic polysaccharide components and that the filaments are probably made up of a peptide core surrounded by polysaccharides.     

Ultrastructural localization of Helix pomatia lectin-binding sites in mouse lung elastic fibers

Summary Helix pomatia (Snail) lectin complexed with colloidal gold (HPL-gold) recognized binding sites on elastic fibers in plastic embedded sections of lung tissue from mice of several ages. Deposition of the lectin-gold particles was examined by electron microscopy. Structures such as the elastic laminae of pulmonary vessels and elastic fibers throughout the lung was specifically and intensely decorated by the HPL-gold complex and easily visualized. The binding of the HPL-gold particles was primarily to sites on the amorphous component of elastin, to the virtual exclusion of the microfibrillar elastin elements, collagen fibers and other components of the extracellular matrix. In addition, moderate age differences in the binding of HPL-gold to elastin were apparent. These observations appear to be the first demonstration of the presence, in the amorphous component of elastin, of glycoconjugates that are specifically recognized by HPL and suggest a method by which the involvement of glycoconjugates in lung elastogenesis could be explored.Supported in part by USPHS Grant HL-32870     

Localization of vanadium-containing particles in the lungs of uranium/vanadium miners

Several geological formations of the Utah-Colorado mining region mined for uranium ore during and after World War II had been mined earlier for vanadium. Therefore, most miners and millers from that region were exposed to those metals’ ores or tailings at one time or another. Preliminary investigation to determine uranium and vanadium retained in the lungs of a former uranium miner and miller from this region, who died of lung cancer (mesothelioma), showed a high nonuniform distribution of vanadium. This observation led to the hypothesis that the vanadium content in the lungs could be associated with inhaled particles. Further examination of spectra of characteristic X-rays obtained by scanning particle-induced X-ray emission (microPIXE) of an autopsy sample of this lung indicated that vanadium was indeed present in localized sites within the 20-μm spatial resolution of the proton beam. This work points out that the microPIXE-RBS (Rutherford backscattering) test for vanadium can be used for site localization of inhaled particles retained in the lungs. Further studies are in progress to: (i) locate uranium-bearing particles in lung tissues of former uranium miners and millers; and (ii) evaluate the local doses of alpha radiation received from these particles.     

MALDI-MS monitoring of differential biomolecule secretion from human lung cells in vitro following incubation with <150 particles

Knowledge of how the chemical composition of a given ambient particle affects varied biological response upon inhalation is of considerable interest regarding the pathogenesis of respiratory and cardiovascular diseases. Characterization of initiating events, using measurements of proinflammatory mediator differential expression by lung tissues, is an objective of our studies. Results demonstrating the capability to monitor changes in the secreted proteome of a human lung cell line culture dosed with <150 particles, for incubation periods ranging from 30 min to 24 h using matrix assisted laser desorption ionization (MALDI) mass spectrometry, are presented. Each population of particles was created within an electrodynamic balance to have the same size and chemical composition prior to being deposited onto a culture of A549 cells. The carbon particles, and the lipopolysaccharide (52 pg/particle) containing carbon particles, were 6.3 microm in diameter. Numerous biomolecules are observable in the mass spectra of supernatants of lung cells. The relative abundance of many of these biomolecules changes as a function of particle type and incubation time, suggesting the ion signal intensities observed are indicative of the relative differential expression of these compounds, some of which could be proinflammatory mediators.     

The reactions of l nm particles of plutonium-238 dioxide and curium-244 dioxide with lung fluid

The reactions of 1 nm particles of plutonium-238 dioxide and curium-244 dioxide with rat lung fluid have been studied both in vitro and in vivo. The plutonium-238 particles are positively charged and combine by electrostatic attraction with the negative pulmonary surfactant which mediates the transfer of radioactivity to the blood. In contrast the curium-244 particles are negative and are assumed to diffuse passively through the alveolar walls. The results emphasise that electrostatic charge is an important factor governing the reaction of 1 nm actinide oxide particles with macromolecules.     

The applicability of hns and fimA primers for detecting Salmonella in bioaerosols associated with animal and municipal wastes

The ability to rapidly screen environmental samples for specific pathogens such as Salmonella spp., is of particular importance in molecular epidemiology. Although gene amplification reactions allow the rapid detection of microorganisms, the use of appropriate oligonucleotide primers targeted against specific microbial genes is critical for accurate detection specificity and sensitivity. Primers such as fimA and hns have been previously shown to be specific for pure cultures of Salmonella. However, the analysis of environmental samples requires post-amplification hybridizations to detect amplicons, since the presence of inhibitory environmental components reduces amplification efficiency of the target organism. These sensitive post-amplification approaches also enable the detection of spurious amplification from non-target sequences. Bioaerosols associated with animal facilities and municipal wastes contain a diverse array of pathogens including Clostridium spp. In our studies, hybridization sensor data revealed spurious amplification of clostridial species with Salmonella hns primers. Specificity checks using type cultures of Clostridium spp. revealed non-specific amplification by hns primers. These results suggest that fimA primers may be better suited to screen Salmonella-specific sequences in environmental samples, especially those obtained from animal and municipal waste facilities.