Influence of colchicine on pulmonary silicotic fibrogenesis in rats

With an aim to evaluate the antifibrotic action of colchicine in experimental model of pulmonary silicosis, the effect of colchicine on developing and developed pulmonary silicosis induced by quartz was studied in rats in vivo and on alveolar macrophages exposed to quartz particulates in vitro. A progressive increase in wet and dry weight of lungs exposed to quartz dust alone, and quartz dust and colchicine injected orally was investigated. An increase in collagen contents, with lapse in time, in animals exposed intratracheally to quartz dust, or exposed similarly to quartz dust but receiving colchicine simultaneously through oral route was observed. A blindfold evaluation of histological sections of lungs of silicotic animals with or without colchicine administration during development of lesions did not reveal any difference between two groups of silicotic rats. Administration of colchicine for 4 weeks after the lesions were developed neither inhibited nor retarded the laying down of collagen. The studies were extended to investigate the effect of colchicine on quartz-induced alveolar macrophage cytotoxicity. The presence of varying concentrations of colchicine in the culture medium did not significantly alter cytotoxic potential of quartz. The results reveal that colchicine administration during the development of and on developed silicosis does not significantly alter pathogenesis of silicotic lesions. At the cellular level colchicine does not modulate quartz-induced alveolar macrophage cytotoxicity, believed to be a significant event for the onset of pulmonary silicotic fibrogenesis.     

Lung Changes in Woodworkers

Pathological changes were observed in the lungs of two workers who had been exposed to wood dust for many years. The cause of death in each case was unrelated to the lung condition. The histopathological changes in the lung were: (1) centrilobular fibrosis and emphysema, (2) the presence of intra-alveolar basophilic particles which had excited a histiocytic and foreign body reaction. Special studies of these bodies tended to confirm the suspicion that they were particles of wood dust. Studies have shown that woodworkers are in an environment heavily saturated with wood dust. The present study suggests that the wood dust is inhaled into the alveoli and may lead to changes in the lungs.     

Biomonitoring of industrial dusts on animals. I. Bioaccumulation of dust components

The bioaccumulation of industrial dust components in laboratory animals exposed by inhalation was studied under environmental conditions. Three types of industrial emissions were investigated: magnesite emissions, wastes from nickel refinery and cement emissions, respectively. The findings revealed that the chemical components of the industrial dust particles inhaled by animals are accumulated not only in the lungs, but also in the other organs, bone and hair of the exposed animals. In addition, the dust components were found in the organs of the F1 generation as well. This suggests a new aspect for the assessment of the biohazard of industrial dust particles in the environment.     

Formation of active forms of oxygen by rat peritoneal macrophages under the effect of cytotoxic dust]

The velocity of superoxide radicals (O2) production by rat peritoneal macrophages, phagocyting the dust particles (quartz and crocidolite-asbestos was measured by using the method of cytochrome c reduction. Generation of hydroxyl radicals (HO) by cells and intensity of lipid peroxidation in the membranes of phagocytes were also investigated. It was found, that under the action of quartz the cells form mainly O2, and under the action of crocidolite--O2 and HO(.). The differences observed were caused by catalytic properties of the surface of asbestos fiber, where the reaction of HO. formation from O2 takes place. The quartz particles increased the concentration of malondialdehyde in macrophages by 53% as compared with control; and lipid peroxidation intensity in the presence of crocidolite-asbestos fibers increased fourfold. The role of hydroxyl radicals in initiating of lipid peroxidation, cytotoxicity and mutagenicity of asbestos is discussed.     

Role of macrophage destruction products in the alveolar phagocytosis reaction]

Peritoneal macrophages (PM) of Wistar rats harvested after the intraperitoneal injection of paraffin oil were destroyed by repeated freezing-thawing. When injected intratracheally to control rats or to those after 4 daily exposured to TiO2 dust, these macrophage destruction products (MDP) caused a significant rise of both the alveolar macrophages (AM) and the neutrophilic leukocytes (NL) counts in the pulmonary washing-outs; the mean NL/AM ratio increased several times as compared to rats injected with normal saline intratracheally. Thus, the response to the inert dust particles plus the exogenous MDP became similar to the one observed after the cytotoxic (for instance silica) particles inhalation. Enhancing the NL contribution to the inhaled particles phagocytosis, the MDP led to a significant decrease of the mean "Dust load" of a single AM, although the total number of the engulfed particles increased. The predominant attraction of granulocytes and particularly of the NL as compared to the peritoneal macrophages was also found in the peritoneal exudates of rats injected with the MDP or silica suspension intraperitoneally, while the alveolar phagocytosis was not influenced. In vitro the MDP was shown to stimulate the NL migration and to facilitate the O2 consumption by PM. A possible role of the MDP as a multipotent controlling factor of phagocytosis response is briefly discussed.     

Abiotic formation of bioorganic compounds in space--preliminary experiments on ground and future exobiology experiments in space.

Simulation experiments on ground have shown that "amino acid precursors", which give amino acids after acid-hydrolysis, can be formed when an ice mixture simulating ice mantles of interstellar dust particles (lSDs) is irradiated with high energy particles or UV light. It is strongly suggested that such bioorganic compounds were delivered by comets for the first biosphere on the Earth. It is of great interest to confirm this hypothesis in actual space conditions, such as in an exposed facility of JEM. Fundamental designs for such exobiology experiments in earth orbit (EEEO) will be discussed.     

Inhibition of the mitochondrial respiratory chain function abrogates quartz induced DNA damage in lung epithelial cells

Respirable quartz dust has been classified as a human carcinogen by the International Agency for Research on Cancer. The aim of our study was to investigate the mechanisms of DNA damage by DQ12 quartz in RLE-6TN rat lung epithelial type II cells (RLE). Transmission electron microscopy and flow-cytometry analysis showed a rapid particle uptake (30 min to 4 h) of quartz by the RLE cells, but particles were not found within the cell nuclei. This suggests that DNA strand breakage and induction of 8-hydroxydeoxyguanosine - as also observed in these cells during these treatment intervals - did not result from direct physical interactions between particles and DNA, or from short-lived particle surface-derived reactive oxygen species. DNA damage by quartz was significantly reduced in the presence of the mitochondrial inhibitors rotenone and antimycin-A. In the absence of quartz, these inhibitors did not affect DNA damage, but they reduced cellular oxygen consumption. No signs of apoptosis were observed by quartz. Flow-cytometry analysis indicated that the reduced DNA damage by rotenone was not due to a possible mitochondria-mediated reduction of particle uptake by the RLE cells. Further proof of concept for the role of mitochondria was shown by the failure of quartz to elicit DNA damage in mitochondria-depleted 143B (rho-0) osteosarcoma cells, at concentrations where it elicited DNA damage in the parental 143B cell line. In conclusion, our data show that respirable quartz particles can elicit oxidative DNA damage in vitro without entering the nuclei of type II cells, which are considered to be important target cells in quartz carcinogenesis. Furthermore, our observations indicate that such indirect DNA damage involves the mitochondrial electron transport chain function, by an as-yet-to-be elucidated mechanism.     

Suppressive oligodeoxynucleotides inhibit silica-induced pulmonary inflammation

Inhalation of silica-containing dust particles induces silicosis, an inflammatory disease of the lungs characterized by the infiltration of macrophages and neutrophils into the lungs and the production of proinflammatory cytokines, chemokines, and reactive oxygen species (ROS). Synthetic oligodeoxynucleotides (ODN) expressing "immunosuppressive motifs" were recently shown to block pathologic inflammatory reactions in murine models of autoimmune disease. Based on those findings, the potential of suppressive ODN to prevent acute murine silicosis was examined. In vitro studies indicate that suppressive ODN blunt silica-induced macrophage toxicity. This effect was associated with a reduction in ROS production and p47phox expression (a subunit of NADPH oxidase key to ROS generation). In vivo studies show that pretreatment with suppressive (but not control) ODN reduces silica-dependent pulmonary inflammation, as manifest by fewer infiltrating cells, less cytokine/chemokine production, and lower levels of ROS (p < 0.01 for all parameters). Treatment with suppressive ODN also reduced disease severity and improved the survival (p < 0.05) of mice exposed to silica.     

Oxidative stress in vivo and in vitro: modulation by quartz dust and hyperbaric atmosphere.

Changes in the oxidative status in the soluble proteins of bronchoalveolar lavage (BAL) fluid from monkeys were examined during 26 months of individual or combined exposure to quartz dust (5 mg/m3 of DQ12) and a hyperbaric atmosphere (2.5 bar). The oxidation of BAL proteins, assumed to be an indicator for oxidative stress in the lungs, was determined by measuring the amount of carbonyl groups in their amino acid side chains. The carbonyl content of BAL proteins (nmol carbonyl/mg protein) increased steadily to a maximum value of 156% of the control after 6 months exposure to hyperbaric atmosphere, and decreased below 50% of control levels in both the quartz alone exposed group and the group exposed to quartz in combination with a hyperbaric atmosphere. The effect of quartz on the production of reactive oxygen species by BAL cells was investigated in vitro. BAL cells from healthy monkeys preincubated with quartz and stimulated with phorbol-myristate acetate (PMA) produced reduced levels of extracellular superoxide anion and intracellular hydrogen peroxide compared with PMA-only stimulated cells. Thus the lowered carbonyl content of BAL proteins in the quartz exposed groups may have resulted from reduced production of the hydrogen peroxide which is essential for carbonyl formation by phagocytes. Changes in carbonyl content of BAL protein in vivo may be a new indicator for potential subsequent lung damage.     

Dynamics of plasma−dust structures formed in a trap created in the narrowing of a current channel in a magnetic field

The geometry and dynamics of plasma?dust structures in a longitudinal magnetic field is studied experimentally. The structures are formed in a glow-discharge trap created in the double electric layer produced as a result of discharge narrowing by means of a dielectric insert introduced in the discharge tube. Studies of structures formed in the new type of glow-discharge trap are of interest from the standpoint of future experiments with complex plasmas in superstrong magnetic fields in which the dust component is magnetized. Different types of dielectric inserts were used: conical and plane ones with symmetric and asymmetric apertures. Conditions for the existence of stable dust structures are determined for dust grains of different density and different dispersity. According to the experimental results, the angular velocity of dust rotation is ≥10 s^–1, which is the fastest type of dust motion for all types of discharges in a magnetic field. The rotation is interpreted by analyzing the dynamics of individual dust grains.     

Heat exchange in dusty plasma

The effect of the charge of a dust grain on the exchange of its heat with plasma particles and with neutral gas particles in an anisotropic dusty plasma with dissipative flows is discussed. It is shown, in particular, that nonuniform heating of the grain surface gives rise to the radiometric force, which may be stronger than the ion wind force. Also, the grain charge causes the thermophoretic force to change its sign.     

Oxidative stress in silicosis: Evidence for the enhanced clearance of free radicals from whole lungs

We hypothesized that reactive oxygen species (ROS) may be involved in the pathogenesis of silicosis. To investigate ROS' dependent pathophysiological processes during silicosis we studied the kinetic clearance of instilled stable nitroxide radicals (TEMPO). Antioxidant enzymes' superoxide dismutase (SOD) and glutathione peroxidase (GPx), and lipid peroxidation were also studied in whole lungs of rats exposed to crystalline silica (quartz) and sham exposed controls. Low frequency L-band electron spin resonance spectroscopy was used to measure the clearance of TEMPO in whole-rat lungs directly. The clearance of TEMPO followed first order kinetics showing significant differences in the rate for clearance between the diseased and sham exposed control lungs. Comparison of TEMPO clearance rates in the sham exposed controls and silicotic rats showed an oxidative stress in the rats exposed to quartz. Studies on the antioxidant enzymes SOD and GPx in the lungs of silicotic and sham exposed animals supported the oxidative stress and accelerated clearance of TEMPO by up regulated levels of enzymes in quartz exposed animals. Increased lipid peroxidation potential in the silicotics also supported a role for enhanced generation of ROS in the pathogenesis of silica-induced lung injury. These in vivo experiments directly demonstrate, for the first time, that silicotic lungs are in a state of oxidative stress and that increased generation of ROS is associated with enhanced levels of oxidative enzymes and lipid peroxidation. This technique offers great promise for the elucidation of ROS induced lung injury and development of therapeutic strategies for the prevention of damage.     

Behaviour of magnetic micro-particles in the human lung

Magnetic micro-particles were used to investigate the defence system of the human lungs against foreign material. Afterprimary magnetisation a remanent magnetic field (RMF) of the lung can be measured that allows estimation of the amount of dust retained in the lung. After calibration of the system with a lung phantom the magnetic contamination retained in the lungs of dental technicians and welders was estimated at mean values of 22 and 500 mg respectively. In normal controls only 0.3 mg was found. About 0.5 mg of spherical monodisperse magnetite particles was deposited in the alveolar region of the lung by voluntary inhalation. The decay of the RMF, calledrelaxation, results from a misalignment of the dipole particles due to the activity of pulmonary macrophages. This macrophage activity is characterised by a cellular energyE _z. With aseconary magnetisation the lung can be remagnetised by rotation of the dipole particles. This allows an estimation of the intracellular viscoelasticity and the motility of the alveolar macrophages in vivo. Secondary magnetisation and relaxation curves of spherical monodisperse magnetite particles are presented. Intracellular viscosity was estimated to be 100 Pa·s at shear rates near 0.01 s^–1, the rigidity modulus beingv 4–8 Pa. Macrophage activity was described by a cellular energyE _z 5·10^–18 J. Additionally, non-magnetic aerosol exposure resulted in a faster relaxation, which was interpreted to be due to activation of the macrophages. The magnetite particles were cleared with a half-time of 110 days.Dedicated to Professor Wolfgang Jacobi on the occasion of his 65th birthday     

Glucose-sensing pulmonary delivery of human insulin to the systemic circulation of rats

In an attempt to achieve post-inhalation self-regulated insulin release, we constructed a microparticle agglomerate of nano-sized liposomal particles, with the agglomeration facilitated by cross-linkages capable of cleavage by glucose. The particles exhibited a small aerodynamic diameter within the human respirable range, but a large geometric diameter that prevents macrophage uptake and clearance. Upon intratracheal instillation of the "glucose-sensitive" microparticle into the lungs of rats, hyperglycemic events triggered an acceleration of the release of insulin achieving normoglycemia shortly after "sensing" the elevated systemic glucose. This work is a demonstration of an inhalable particle with long residence times in the lungs capable of modulating insulin release based on systemic glucose levels.     

Determination of urban pollution islands by using remote sensing technology in Moscow,Russia

Pollution of the atmosphere with harmful substances is currently the most dangerous form of degradation of the natural environment in Russia. The peculiarities of the environmental situation and the emerging environmental problems in some areas of the Russian Federation are caused by local natural conditions and the nature of the impacts from industries, transport, utilities, and agriculture (the specifics of enterprises, their capacity, location, technologies used). As a rule, the magnitude of air pollution depends on the degree of urbanization and anthropogenic transformation of the territory and climatic conditions that determine the potential for atmospheric pollution. During high-temperature technological processes, the smallest aerosol particles (0.5..0.10 μm) formed, poorly captured by gas purification plants, and can migrate in the atmosphere for considerable distances. Larger particles (2.5 μm and above) are formed due to the mechanical decomposition of solid particles and enter the atmosphere due to wind erosion, the dusting of dirt roads, the erasure of vehicle tires. The particles suspended with a diameter of not more than 2.5 μm (PMX) are the most destructive to health since they penetrate and get deposited deep into human lungs. These microns, present in a suspended state in the air, consist of a complex mixture of large and small, solid and liquid particles, of both inorganic and organic substances. The boundary between the two fractions is usually particles with a diameter of 2.5 μm (PM2.5). This study sought to build a model for determining fine dust PM2.5 in the Moscow air environment using Landsat 8 OLI satellite image channels and data on the concentrations of fine dust PM2.5 obtained by weather stations in the city. In addition, a correlation analysis was carried out to determine a regression model for studying the dispersion of fine dust in the city. The results obtained are presented on a map of the concentration of fine dust PM2.5 in Moscow, supporting management decisions and decision-making on environmental policy in urban planning.     

Reaction of cysteine and glutathione (GSH) at the freshly fractured quartz surface: a possible role in silica-related diseases?

The reactivity of quartz dusts towards glutathione (GSH) and cysteine (Cys) has been investigated. Cys and GSH react, without being adsorbed (UV-Vis spectroscopy), with commercial quartz dusts in an exposed surface-dependent way, but not with amorphous silica. GSH and Cys have been contacted with freshly ground quartz (agate jar QZg-a and steel jar QZg-s) and quartz heated in air at 500 degrees C (QZs-500) and with a dust generated from a purified quartz (99.9999%) to detect the nature of the reacting surface sites. With both GSH and Cys, the highest reactivity was found on the particles ground in a steel jar, while pure quartz was fully inactive. Detection of the radical GS* (spin trapping) suggests a radical mechanism of oxidation to disulphide onto surface-bound iron traces, more abundant on QZg-s and absent on the pure quartz. Oxidation of thiol groups occurs at surface sites different from those involved in the homolytic rupture of a C-H bond. Both reactions are more pronounced on freshly ground samples, but the C-H rupture takes place at silicon-based surface radicals and Fe2+ centers, while oxidation of GSH and Cys requires Fe3+ centers. As all commercial quartz dusts contain surface iron as an impurity, depletion of extracellular or intracellular GSH may contribute to the oxidative damage caused by particle-derived and cell-derived reactive oxygen species.     

A method for determining the dielectric constant and the conductivity of membrane-bounded particles of biological relevance.

Numerical assessment is made regarding Pauly and Schwan's theory which describes the dielectric behavior of a suspension of "shell spheres" as a model of biological membrane-bounded particles. The results indicate that approximate expressions of the theory may give rise to serious errors when applied to particles smaller than about 1 mum in diameter. With a view to performing analysis according to a general expression of the theory, some of the characteristic responses of dielectric parameters upon changes in phase parameters are examined with particular reference to some numerical ranges of biological interest. On this basis a simplified and systematic procedure is proposed for estimating the phase parameters of particles whose shell phase can be regarded as non-conductive. As the application of the procedure proposed, a set of dielectric data of a synaptosome suspension is analyzed, so that the following three phase parameters are successfully determined: membrane capacitance (or shell phase dielectric constant), interval phase conductivity and internal phase dielectric constant. Some limitations of the procedure are discussed for the cases of conducting shells and small particles.     

Transmembrane flux and receptor desensitization measured with membrane vesicles. Homogeneity of vesicles investigated by computer simulation.

The use of membrane vesicles to make quantitative studies of transmembrane transport and exchange processes involves an assumption of homogeneity of the membrane vesicles. In studies of 86Rb+ exchange mediated by acetylcholine receptor from the electric organ of Electrophorus electricus and of 36Cl- exchange mediated by GABA receptor from rat brain, measurements of ion exchange and receptor desensitization precisely followed first order kinetics in support of this assumption. In other measurements a biphasic decay of receptor activity was seen. To elucidate the molecular properties of receptors from such measurements it is important to appreciate what the requirements of vesicle monodispersity are for meaningful results and what the effect of vesicle heterogeneity would be. The experiments were simulated with single vesicle populations with variable defined size distributions as well as with mixtures of different populations of vesicles. The properties of the receptors and their density in the membrane could be varied. Different receptors could be present on the same or different membrane vesicles. The simulated measurements were not very sensitive to size dispersity. A very broad size distribution of a single vesicle population was necessary to give rise to detectable deviations from first order kinetics or errors in the determined kinetic constants. Errors could become significant with mixtures of different vesicle populations, where the dispersity in initial ion exchange rate constant, proportional to the receptor concentration per internal volume, became large. In this case the apparent rate of receptor desensitization would diverge in opposite directions from the input value when measured by two different methods, suggesting an experimental test for such kinetic heterogeneity. A biphasic decrease of receptor activity could not be attributed to vesicle heterogeneity and must be due to desensitization processes with different rates. Significant errors would not arise from the size dispersity apparent in subpopulations of vesicles seen by imaging techniques in membrane preparations.     

Abdominal segment formation in Spirorbis moerchi (Polychaeta)

Summary The development of abdominal segments in Spirorbis moerchi (Polychaeta: Annelida) was studied by light and electron microscopy. Abdominal segments develop in strict succession from anterior to posterior. Segmentation is initiated in the mesoderm and is followed by segmentation of the ectoderm. The mesoderm of the abdominal segments arises entirely from pygidial residual mesoderm; inward migration of cells from the pygidial ectoderm to give rise to mesoderm does not occur. The primordial germ cells remain distinct from the residual mesoderm of the pygidial growth region. After several abdominal segments have developed, the primordial germ cells migrate posteriorly from the achaetous region, invade the abdominal segments, and give rise to the retroperitoneal gonads. Abdominal segment formation is discussed in terms of heteronomy, primordial germ cell origin, gonad formation, and development of the circulatory system.     

Effects of mineral dust on generation of superoxide radicals and hydrogen peroxide by alveolar macrophages, granulocytes and monocytes

Phagocytosis of quartz dust by alveolar macrophages and monocytes of rabbits and human monocytes and granulocytes is accompanied by stimulation of substrateless recovery of nitroblue tetrazolium to formazan. It reflects activation of oxygen-dependent bactericidal phagocyte system and generation of active oxygen forms. Less fibrogenic and cytotoxic dust of aluminium oxide increased formazan formation insignificantly. Extracellular generation of superoxide radicals and hydrogen peroxide was not discovered during phagocytosis of quartz by alveolar macrophages and monocytes. Incubation of human granulocytes with silica caused, on contrary, considerable increase in exogenous generation of superoxide radicals and hydrogen peroxide. Less fibrogenic dust of aluminium oxide under the conditions had no effect on generation of hydrogen peroxide and induced acute decrease in generation of superoxide radicals by granulocytes. The obtained results testify both to the essential part of active oxygen form during pathologic processes with pneumoconiosis, and also to a great similarity among biochemical processes, characterizing interaction of alveolar macrophages and monocytes with mineral dust.