ROS-mediated TNF-alpha and MIP-2 gene expression in alveolar macrophages exposed to pine dust

BACKGROUND: Respiratory symptoms, impaired lung function, and asthma have been reported in workers exposed to wood dust in a number of epidemiological studies. The underlying pathomechanisms, however, are not well understood. Here, we studied the effects of dust from pine (PD) and heat-treated pine (HPD) on the release of reactive oxygen species (ROS) and inflammatory mediators in rat alveolar macrophages. METHODS: Tumour necrosis factor-alpha (TNF-alpha) and macrophage inflammatory protein-2 (MIP-2) protein release, TNF-alpha and MIP-2 mRNA expression, and generation of ROS were studied as end points after treatment of rat alveolar macrophages with PD or HPD. In a separate series of experiments, the antioxidants glutathione and N-acetyl-L-cysteine were included in combination with wood dust. To determine the endogenous oxidative and antioxidant capacity of wood dusts, electron spin resonance (ESR) spectroscopy was used. RESULTS: After 4 h incubation, both PD and HPD elicited a significantly (p < 0.05) increased mRNA expression of TNF-alpha and MIP-2 as well as a concentration-dependent release of TNF-alpha and MIP-2 protein. Interestingly, PD induced a significantly higher TNF-alpha and MIP-2 production than HPD. Moreover, a significantly increased ROS production was observed in alveolar macrophages exposed to both PD and HPD. In the presence of the antioxidants glutathione and N-acetyl-L-cysteine, the PD- and HPD-induced release of ROS, TNF-alpha, and MIP-2 was significantly reduced. Finally, electron spin resonance analyses demonstrated a higher endogenous antioxidant capacity of HPD compared to PD. Endotoxin was not present in either dust sample. CONCLUSION: These results indicate that pine dust is able to induce expression of TNF-alpha and MIP-2 in rat alveolar macrophages by a mechanism that is, at least in part, mediated by ROS.     

ROS-mediated TNF-α and MIP-2 gene expression in alveolar macrophages exposed to pine dust

Background  

Respiratory symptoms, impaired lung function, and asthma have been reported in workers exposed to wood dust in a number of epidemiological studies. The underlying pathomechanisms, however, are not well understood. Here, we studied the effects of dust from pine (PD) and heat-treated pine (HPD) on the release of reactive oxygen species (ROS) and inflammatory mediators in rat alveolar macrophages.     

Transfer of arachidonate from phosphatidylcholine to phosphatidylethanolamine and triacylglycerol in guinea pig alveolar macrophages

Guinea pig alveolar macrophages were labeled by incubation with either arachidonate or linoleate. Arachidonate labeled phosphatidylcholine (PC), phosphatidylethanolamine (PE) and triglycerides (TG) equally well, with each lipid containing about 30% of total cellular radioactivity. In comparison to arachidonate, linoleate was recovered significantly less in PE (7%) and more in TG (47%). To investigate whether redistributions of acyl chains among lipid classes took place, the macrophages were incubated with 1-acyl-2-[1-¹⁴C]arachidonoyl PC or 1-acyl-2-[1-¹⁴C]linoleoyl PC. After harvesting, the cells incubated with 1-acyl-2-[1-¹⁴C]linoleoyl PC contained 86% of the recovered cellular radioactivity in PC, with only small amounts of label being transferred to PE and TG (3 and 6%, respectively). More extensive redistributions were observed with arachidonate-labeled PC. In this case, only 60% of cellular radioactivity was still associated with PC, while 22 and 12%, respectively, had been transferred to PE and TG. Arachidonate transfer from PC to PE was unaffected by an excess of free arachidonate which inhibited this transfer to TG for over 90%, indicating that different mechanisms or arachidonoyl CoA pools were involved in the transfer of arachidonate from PC to PE and TG. Cells prelabeled with 1-acyl-2-[1-¹⁴C]arachidonoyl PC released¹⁴C-label into the medium upon further incubation. This release was slightly stimulated by zymosan and threefold higher in the presence of the Ca²⁺-ionophore A₂₃₁₈₇. Labeling of macrophages with intact phospholipid molecules appears to be a suitable method for studying acyl chain redistribution and release reactions.     

In vitro toxicoproteomic analysis of A549 human lung epithelial cells exposed to urban air particulate matter and its water-soluble and insoluble fractions

Background

Toxicity of airborne particulate matter (PM) is difficult to assess because PM composition is complex and variable due to source contribution and atmospheric transformation. In this study, we used an in vitro toxicoproteomic approach to identify the toxicity mechanisms associated with different subfractions of Ottawa urban dust (EHC-93).

Methods

A549 human lung epithelial cells were exposed to 0, 60, 140 and 200 μg/cm² doses of EHC-93 (total), its insoluble and soluble fractions for 24 h. Multiple cytotoxicity assays and proteomic analyses were used to assess particle toxicity in the exposed cells.

Results

The cytotoxicity data based on cellular ATP, BrdU incorporation and LDH leakage indicated that the insoluble, but not the soluble, fraction is responsible for the toxicity of EHC-93 in A549 cells. Two-dimensional gel electrophoresis results revealed that the expressions of 206 protein spots were significantly altered after particle exposures, where 154 were identified by MALDI-TOF-TOF-MS/MS. The results from cytotoxicity assays and proteomic analyses converged to a similar finding that the effects of the total and insoluble fraction may be alike, but their effects were distinguishable, and their effects were significantly different from the soluble fraction. Furthermore, the toxic potency of EHC-93 total is not equal to the sum of its insoluble and soluble fractions, implying inter-component interactions between insoluble and soluble materials resulting in synergistic or antagonistic cytotoxic effects. Pathway analysis based on the low toxicity dose (60 μg/cm²) indicated that the two subfractions can alter the expression of those proteins involved in pathways including cell death, cell proliferation and inflammatory response in a distinguishable manner. For example, the insoluble and soluble fractions differentially affected the secretion of pro-inflammatory cytokines such as MCP-1 and IL-8 and distinctly altered the expression of those proteins (e.g., TREM1, PDIA3 and ENO1) involved in an inflammatory response pathway in A549 cells.

Conclusions

This study demonstrated the impact of different fractions of urban air particles constituted of various chemical species on different mechanistic pathways and thus on cytotoxicity effects. In vitro toxicoproteomics can be a valuable tool in mapping these differences in air pollutant exposure-related toxicity mechanisms.

     

The phospholipids of rabbit type II alveolar epithelial cells: Comparison with lung lavage,lung tissue,alveolar macrophages,and a human alveolar tumor cell line

The phospholipid composition of type II alveolar epithelial cells from the rabbit was compared with that of alveolar macrophages, lung lavage and lung tissue. In addition, the phospholipid composition of a human alveolar tumor cell line, which is morphologically similar to type II cells, was examined. Phosphatidylcholine accounted for 48% of the total phospholipid in the type II cells, 41% in the tumor cells, and 30% in the macrophages. Phosphatidylcholine was 51% disaturated in the type II cells, 54% in lung lavage, 39% in whole lung, 29% in lavaged lung and macrophages, and 16% in the tumor cells. Palmitic acid was the major fatty acid in phosphatidylcholine from all samples with the exception of the tumor cells in which almost half of the fatty acids were accounted for by oleic acid. The phospholipids of the type II cells were more similar to those of lung lavage, and thus surfactant, than to lung tissue and macrophages. This is consistent with their supposed role in surfactant production. The tumor cells, although morphologically similar to type II cells, were quite different with respect to phospholipid composition.     

An easy correlation to determine soluble and insoluble fractions in diesel particulate matter

Mathematical fitting of experimental emission data from five different fuels and three mixtures of biodiesel and reference diesel operating under diverse conditions allows to propose an easy equation to calculate both the insoluble and soluble fractions in Diesel Particulate Matter.

The relative importance of each mechanism involved in the DPM formation process is also mathematically quantified. Two different mechanisms are principally found to take place during DPM formation. In a first stage (scrubbing effect), adsorbed sulphuric acid reacts with organic compounds in the exhaust to form heavy hydrocarbons which are likely to remain in the condensed phase. The remaining hydrocarbons undergo an absorption process and are retained on particles in the liquid phase. However, some light hydrocarbons may escape from the filter system and are not quantified as soluble organic fraction (SOF). The presence of two retention mechanisms makes it necessary to develop an accurate extraction technique to quantify the soluble organic fraction.     

燃煤电厂可凝结颗粒物检测方法、排放特征及脱除技术研究进展

燃煤电厂排放的颗粒物分可过滤颗粒物（filterable particulate matter,FPM）和可凝结颗粒物（condensable particulate matter,CPM）。过去,人们对CPM的关注较少,但其对环境与人体具有危害。本文综述了CPM的检测方法,主要有撞击冷凝法和稀释冷凝法,开发在线及小型便携设备是CPM检测技术的发展方向。分析了燃煤电厂CPM的排放特征,CPM占燃煤电厂排放总颗粒物的比重较高,经超低排放改造后,CPM占比进一步提升,各燃煤电厂排放的CPM的组分差异较大。根据CPM的特性,未来对CPM控制技术的研究方向为冷凝、吸附、湿式电除尘等。最后基于当前CPM的研究现状,建议国家相关部门制定对燃煤电厂等固定污染源排放的CPM的检测标准并对实施超低排放改造的燃煤电厂建立源排放清单,对新建、处于环境敏感地带以及排烟带有明显“有色烟羽”现象的燃煤电厂,合理管控其CPM的排放。     

Muscle Diversity,Heterogeneity, and Gradients: Learning from Sarcoglycanopathies

Skeletal muscle, the most abundant tissue in the body, is heterogeneous. This heterogeneity forms the basis of muscle diversity, which is reflected in the specialized functions of muscles in different parts of the body. However, these different parts are not always clearly delimitated, and this often gives rise to gradients within the same muscle and even across the body. During the last decade, several studies on muscular disorders both in mice and in humans have observed particular distribution patterns of muscle weakness during disease, indicating that the same mutation can affect muscles differently. Moreover, these phenotypical differences reveal gradients of severity, existing alongside other architectural gradients. These two factors are especially prominent in sarcoglycanopathies. Nevertheless, very little is known about the mechanism(s) driving the phenotypic diversity of the muscles affected by these diseases. Here, we will review the available literature on sarcoglycanopathies, focusing on phenotypic differences among affected muscles and gradients, characterization techniques, molecular signatures, and cell population heterogeneity, highlighting the possibilities opened up by new technologies. This review aims to revive research interest in the diverse disease phenotype affecting different muscles, in order to pave the way for new therapeutic interventions.     

Cardiovascular effects in patrol officers are associated with fine particulate matter from brake wear and engine emissions

Background  

Exposure to fine particulate matter air pollutants (PM_2.5) affects heart rate variability parameters, and levels of serum proteins associated with inflammation, hemostasis and thrombosis. This study investigated sources potentially responsible for cardiovascular and hematological effects in highway patrol troopers.     

Infant cerebellar gray and white matter fatty acids in relation to age and diet

There is little evidence as to the fatty acid composition of the cerebellum in infancy and it remains uncertain whether milk diet can influence its composition. We therefore examined cerebellar gray and white matter of infants less than 6 mon old who had died unexpectedly. The fatty acid content of 33 gray and 21 white matter specimens from infants born at term and 6 gray and 5 white matter specimens from pretern infants was assessed by gas chromatographic/mass spectrometric analysis. Infants were grouped according to whether they had received human or manufactured formula milk. Whereas cerebellar cortex docosahexaenoic acid (DHA, 22∶6n−3) concentrations were significantly lower (P<0.01) in the formula-fed than breast-fed infants, no differences existed between the term (n=10) and preterm (n=5) Scientific Milk Adaptation (SMA) formula-fed infants. Cerebellar white matter DHA concentrations were similarly lower (P<0.01) in the SMA formula-fed infants (n=8) than in an age-matched breast-fed group. Low concentrations of cerebellar white matter lignoceric (24∶0) and nervonic acid (24∶1n−9) in two 7-wk-old preterm infants appeared to correlated with postgestational rather than chronological age. Dietary long-chain polyunsaturated fatty acids particularly DHA, are probably essential for normal development of the infant cerebellum.     

Simulation of aerosol dynamics and transport in chemically reacting particulate matter laden flows. Part II: Application to CVD reactors

A highly computationally efficient and accurate semi-implicit numerical technique based on the concept of operator splitting (described in detail in Part I of this paper) has been used to solve the General Dynamic Equation in complex, non-isothermal reacting flows to predict aerosol dynamics and particle deposition rates. The numerically efficient algorithm has made it possible to solve the GDE in complex two-dimensional and three-dimensional simulations, hitherto not done due to the computational intensiveness. Simulations have been performed to elucidate the role of different process parameters on aerosol dynamics and particle deposition rates in idealized and commercial horizontal single wafer CVD reactors. Specifically, it has been demonstrated that the gas phase kinetics, particle formation, growth and deposition rates result in very complex aerosol size distributions in the reactor that cannot be captured with simplistic models that do not couple the GDE to the detailed flow field simulations. Guidelines for minimizing particle contamination in CVD reactors on the basis of the simulation results are presented.     

Properties of water-soluble and insoluble particulate matter emitted from dewatered sewage sludge incineration in a pilot-scale ash melting furnace

Emission of inorganic particulate matter (PM) from the incineration of dewatered sewage sludge has been investigated in a novel ash melting furnace. The sludge containing 79 wt% water was incinerated in an oxygen-enriched atmosphere at the primary temperature of 1400 °C, and its unburned volatile was combusted at 1100 °C in a secondary combustion chamber. A 13-stage low-pressure-impactor and the conventional impinger methods were employed for PM sampling at the outlet of the secondary combustion chamber. The results indicate that, PM is dominated by volatile and semi-volatile elements including Br, Cl, P, S, Na, K, Zn, As, Cu, Mn and Ni. Less refractory elements were found. PM has two major fractions: <0.22 and ?0.22 μm. Their chemical forms as well as water solubility are different between two fractions. The majority of Br, nearly half of Cl, and 40% of S and P are present in the small fraction. They are mostly water-soluble due to the association with alkali elements and heavy metals. The water-insoluble calcium sulfate and calcium/iron phosphate were, however, found in the large fraction of PM. Regarding the cations, the water solubilities of Na, K, Mn and Ni are close to their proportions partitioned into the small fraction of PM, since their water-soluble species were preferentially formed in this fraction. A relatively weak correlation for Al, Ca and As, while no such a correlation were found for Cu, Zn and Fe, due to the complex compounds formed for them.     

Effects of particulate matter on the pulmonary and vascular system: time course in spontaneously hypertensive rats

Background  

This study was performed within the scope of two multi-center European Commission-funded projects (HEPMEAP and PAMCHAR) concerning source-composition-toxicity relationship for particulate matter (PM) sampled in Europe. The present study aimed to optimize the design for PM in vivo toxicity screening studies in terms of dose and time between a single exposure and the determination of the biological responses in a rat model mimicking human disease resulting in susceptibility to ambient PM. Dust in thoracic PM size-range (aerodynamic diameter <10 μm) was sampled nearby a road tunnel (RTD) using a high volume cascade impactor. Spontaneously hypertensive rats were exposed to urban dust collected in Ottawa, Canada (EHC-93 10 mg/kg of body weight; reference PM) or different RTD doses (0.3, 1, 3, 10 mg/kg of body weight) by intratracheal instillation. Necropsy was performed at 4, 24, or 48 hr after exposure.     

Part II: Dynamic evolution of the particle size distribution in particulate processes undergoing simultaneous particle nucleation, growth and aggregation

The present study provides a comprehensive investigation on the solution of the dynamic population balance equation (PBE) for particulate processes undergoing simultaneous particle nucleation, growth and aggregation. The general PBE was numerically solved in both the continuous and its equivalent discrete form using the orthogonal collocation on finite elements and the discretized PBE method, respectively. A detailed investigation on the effect of particle nucleation rate on the calculated particle size distribution (PSD) was carried out over a wide range of variation of dimensionless aggregation, nucleation and growth times. The performance (i.e., accuracy and stability) of the two numerical methods was assessed by a direct comparison of predicted PSDs and/or their respective moments to available analytical solutions. For combined aggregation and nucleation problems, the numerical error scaled with the product of the dimensionless aggregation and nucleation times. On the other hand, for combined growth and nucleation problems, the numerical error scaled only with the dimensionless growth time. For particulate systems with minimal particle growth, constant particle nucleation rate and Brownian aggregation, the total particle number approached a “steady-state” value characterized by the equilibrium of particle aggregation and nucleation rates. When the particle nucleation rate followed a pulse-like function, the PSD converged to a self-similar distribution after the end of particle nucleation. Moreover, for particulate systems exhibiting a constant particle nucleation rate and a Brownian-type particle aggregation kernel, an increase in the particle growth rate resulted in a decrease in the final total number of particles. On the other hand, for a constant particle nucleation rate and an electrostatically stabilized Brownian aggregation kernel, an increase in the particle growth rate can lead to an increase in the final total number of particles.     

Sintering and technical properties of silicon carbide heaters in relation to the grain size

Conclusions Sintering of blanks of SiC of different grain-size distributions is accompanied by slight recrystallization and the appearance of fine grains not present in the original silicon carbide.During siliciding firing of heaters by passing an electric current, we form secondary silicon carbide, silicon, silica, and carbon monoxide. Under these conditions the silicon and carbon monoxide, and also the oxides of alkaline metals, are volatilized.We also note volatilization of silicon carbide, especially of the fine grains from the surface of the heaters. This is indicated by the sharp increase in loss in weight and partial shrinkage over the diameter of the heaters made from bodies containing large quantities of fine fractions.For industrial use, it is necessary to test two and three fractional size gradings in which, in addition to coarse fractions, there are up to 20% grains measuring 20–50 . The use for manufacturing heaters of monofraction compositional bodies or those containing, in addition to coarse grains, a substantial quantity of grains finer than 20, is undesirable.Translated from Ogneupory, No. 2, pp. 43–45, February, 1966.