Acute toxicity of organoarsenic chemical warfare agents to Danio rerio embryos

During the 20th century, thousands of tons of munitions containing organoarsenic chemical warfare agents (CWAs) were dumped into oceans, seas and inland waters around the world. As a result, organoarsenic CWAs continue to leak from corroding munitions into sediments and their environmental concentrations are expected to peak over the next few decades. There remains, however, a lack of knowledge about their potential toxicity to aquatic vertebrates, such as fish. The aim of this study was to fill in this gap in research, by investigating the acute toxicity of organoarsenic CWAs on fish embryos, using the model species, Danio rerio. To estimate the acute toxicity thresholds of organoarsenic CWAs (Clark I, Adamsite, PDCA), a CWA-related compound (TPA), as well as four organoarsenic CWA degradation products (Clark I[ox], Adamsite[ox], PDCA[ox], TPA[ox]), standardized tests were performed following the OECD no. 236 Fish Embryo Acute Toxicity Test guidelines. Additionally, the detoxification response in D. rerio embryos was investigated by analysing the mRNA expression of five genes encoding antioxidant enzymes (CAT, SOD, GPx, GR and GST). During the 96 h of exposure, organoarsenic CWAs induced lethal effects in D. rerio embryos at very low concentrations (classified as 1st category pollutants according to GHS categorization), and were therefore deemed to be serious environmental hazards. Although TPA and the four CWA degradation products caused no acute toxicity even at their maximum solubility, the transcription of antioxidant-related genes was altered upon exposure to these compounds, indicating the need for further testing for chronic toxicity. Incorporating the results of this study into ecological risk assessments will provide a more accurate prediction of the environmental hazards posed by CWA-related organoarsenicals.

Analysis of the Morphology and Structure of Carbon Deposit Formed on the Surface of Ni3Al Foils as a Result of Thermocatalytic Decomposition of Ethanol

This article presents the results of investigations of the morphology and structure of carbon deposit formed as a result of ethanol decomposition at 500 °C, 600 °C, and 700 °C without water vapour and with water vapour (0.35 and 1.1% by volume). scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) observations as well as energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), and Raman spectroscopic analyses allowed for a comprehensive characterization of the morphology and structure of cylindrical carbon nanostructures present on the surface of the Ni₃Al catalyst. Depending on the reaction mixture composition (i.e., water vapour content) and decomposition temperature, various carbon nanotubes/carbon nanofibres (CNTs/CNFs) were observed: multiwalled carbon nanotubes, herringbone-type multiwall carbon nanotubes, cylindrical carbon nanofibers, platelet carbon nanofibers, and helical carbon nanotubes/nanofibres. The discussed carbon nanostructures exhibited nickel nanoparticles at the ends and in the middle part of the carbon nanostructures as catalytically active centres for efficient ethanol decomposition.

Acute aquatic toxicity of arsenic-based chemical warfare agents to Daphnia magna

Sea dumping of chemical warfare (CW) took place worldwide during the 20th century. Submerged CW included metal bombs and casings that have been exposed for 50-100 years of corrosion and are now known to be leaking. Therefore, the arsenic-based chemical warfare agents (CWAs), pose a potential threat to the marine ecosystems. The aim of this research was to support a need for real-data measurements for accurate risk assessments and categorization of threats originating from submerged CWAs. This has been achieved by providing a broad insight into arsenic-based CWAs acute toxicity in aquatic ecosystems. Standard tests were performed to provide a solid foundation for acute aquatic toxicity threshold estimations of CWA: Lewisite, Adamsite, Clark I, phenyldichloroarsine (PDCA), CWA-related compounds: TPA, arsenic trichloride and four arsenic-based CWA degradation products. Despite their low solubility, during the 48 h exposure, all CWA caused highly negative effects on Daphnia magna. PDCA was very toxic with 48 h D. magna LC50 at 0.36 μg × L^-1 and Lewisite with EC50 at 3.2 μg × L^-1. Concentrations at which no immobilization effects were observed were slightly above the analytical Limits of Detection (LOD) and Quantification (LOQ). More water-soluble CWA degradation products showed no effects at concentrations up to 100 mg × L^-1.

The effects of chemical warfare agent Clark I on the life histories and stable isotopes composition of Daphnia magna

Chemical warfare agents (CWA) dumped worldwide in all types of aquatic reservoirs pose a potential environmental hazard. Leakage of CWAs from eroding containers at dumping sites had been observed, and their presence in the tissues of aquatic animals was confirmed. However, the ecological effects of CWA have not yet been studied. In standardized laboratory bioassays, we tested if sublethal concentration of Clark I, an arsenic based CWA, can affect life histories (somatic growth rate, fecundity, size at maturity), population growth rate and stable isotope signatures of a keystone crustacean grazer Daphnia magna. We found that the life histories and fitness of daphnids reared in the presence of Clark I differed from those reared in Clark-free conditions. The effects were observed when Clark I concentrations were no less than 5 μg×L^-1. With increasing concentrations of the tested CWA, all of the tested parameters decreased linearly. The finding indicates that even sublethal concentrations of Clark I can affect crustacean populations, which should be taken into account when assessing the environmental risks of this particular CWA. We found intraspecific diversity in susceptibility to Clark I, with some clones being significantly less vulnerable than others. We also found that in the presence of Clark I, the ratio of heavy and light isotopes of nitrogen in the bodies of daphnids was affected - daphnids exhibited δ¹⁵N enrichment with increasing concentrations of this CWA. The isotopic composition of carbon was not affected by the presence of Clark I. The nitrogen isotopic signature may be used as an indicator of stress in zooplankton exposed to the presence of toxic xenobiotics.

Acute aquatic toxicity of sulfur mustard and its degradation products to Daphnia magna

Sulphur mustard (HD) was the most widely produced chemical warfare agent (CWA) in the history of chemical warfare (CW). Simultaneously, the loads of HD account as by far the largest fraction of the sea-dumped CW. Nowadays its presence in the marine ecosystems recognized as a serious threat for marine users and maritime industries. Although, during over a decade of research much has been done to assess the environmental threats linked with underwater chemical munitions. There are, however, essential gaps in scientific knowledge including scarce information about the aquatic toxicity thresholds of HD and its degradation products. Standardized biotests were performed according to the Organisation for Economic Co-operation and Development (OECD) Test No. 202: Daphnia sp. Acute Immobilisation Test guidelines. Obtained results provide a solid foundation for comparison and categorisation of threats of HD and its degradation products. With the D. magna LC₅₀ aquatic acute toxicity threshold at as low as 224 ± 12 μg × L^-1, 1,2,5-trithiepane is very toxic, being one of the most toxic CWA degradation products that have been investigated up to date. It exhibits stronger effects than 1,4,5-oxadithiepane and diluted HD that turn out to be toxic. In total, the toxicity of 7 compounds has been estimated. Whenever possible, toxicity thresholds were compared with previously existing data originating from different biotests and mathematical modelling.

Exposure status of sea-dumped chemical warfare agents in the Baltic Sea

About 50 000 tons of chemical weapons (CW) were dumped to the Baltic Sea after the Second World War. Munitions are located in the deep areas of the Baltic Sea, and there they act as a point source of contamination to the ecosystem. Corroded munitions release chemical warfare agents (CWAs) to nearby water and sediments. In this study we investigated known dumpsites (Bornholm, Gotland and Gdansk Deep) and dispersed chemical munitions, to evaluate the extent of contamination of nearby sediments, as well as to assess the degradation process of released CWA. It was found that CWA-related phenylarsenic chemicals (Clark I, Clark II and Adamsite) and sulfur mustard are released to the sediments and undergo environmental degradation to chemicals, of which some remain toxic. The extent of pollution of released CWAs and their corresponding degradation products reaches more than 250 m from the CW objects, and seem to follow a power curve decrease of concentration from the source. Bornholm Deep is characterised with the highest concentration of CWAs in sediments, but occasional concentration peaks are also observed in the Gdansk Deep and close to dispersed munitions. Detailed investigation of spreading pattern show that the range of pollution depends on bottom currents and topography.

Analysis of samples of explosives excavated from the Baltic Sea floor

After World War II, conventional and chemical ammunition containing mainly secondary and primary explosives was dumped in the sea. Explosives have medium toxicity to aquatic organisms, earthworms and indigenous soil microorganisms. Therefore, environmental monitoring is required, especially for dumped munitions. The main aspect of this work was to analyse the samples of lumps and sediments taken from the Baltic seabed. These samples were potentially explosives. The main goal of the study was to identify the type and composition of studied materials. In order to determine the chemical composition of samples of explosives, we used as follows: GC-MS/MS, LC-HRMS and NMR. Additionally, to determine the energetic properties we performed microcalorimetric-thermogravimetric analysis. Based on the obtained results, the composition of this explosive was TNT (41%), RDX (53%), aluminium powder (5%), and degradation products (below 1%). The resulting composition indicates that the analysed material can be classified in the "torpex" family, widely used during World War II. Regarding the results of the microcalorimetric analysis, we can conclude that excavated fragments of explosives are in very good condition and they still can detonate after being initiated. Therefore, there is a threat that they could be used for criminal or terrorist purposes.

Development of analytical methods used for the study of 2,4,6-trinitrotoluene degradation kinetics in simulated sediment samples from the Baltic Sea

Large amounts of ammunition containing 2,4,6-trinitrotoluene (TNT) and other substances were dumped in the Baltic Sea after WWII. Considering progressive corrosion processes, studying the transformation of TNT occurring in the environment constitutes an important aspect of a possible associated risk. This study focused on the transformations of TNT in simulated conditions of the Baltic Sea bottom sediment. Methods of analysis of TNT and selected products of its transformations were developed for that purpose. The developed methods allowed for the determination of selected compounds below 1 ng/g. Systematic monitoring of TNT transformations in the environment of the bottom sediment was performed. This allowed for the determination of the kinetics of TNT degradation and identification of degradation reaction products. Based on the obtained results, the TNT decay half-time in conditions present in the Baltic Sea was estimated to be 16.7 years for the abiotic environment and 5.6 for the biotic environment.

Feasibility study of using brine for carbon dioxide capture and storage from fixed sources

A laboratory-scale reactor was developed to evaluate the capture of carbon dioxide (CO2) from a gas into a liquid as an approach to control greenhouse gases emitted from fixed sources. CO2 at 5-50% concentrations was passed through a gas-exchange membrane and transferred into liquid media--tap water or simulated brine. When using water, capture efficiencies exceeded 50% and could be enhanced by adding base (e.g., sodium hydroxide) or the combination of base and carbonic anhydrase, a catalyst that speeds the conversion of CO2 to carbonic acid. The transferred CO2 formed ions, such as bicarbonate or carbonate, depending on the amount of base present. Adding precipitating cations, like Ca++, produced insoluble carbonate salts. Simulated brine proved nearly as efficient as water in absorbing CO2, with less than a 6% reduction in CO2 transferred. The CO2 either dissolved into the brine or formed a mixture of gas and ions. If the chemistry was favorable, carbonate precipitate spontaneously formed. Energy expenditure of pumping brine up and down from subterranean depths was modeled. We conclude that using brine in a gas-exchange membrane system for capturing CO2 from a gas stream to liquid is technically feasible and can be accomplished at a reasonable expenditure of energy.

Multiple metastases of carcinoma basocellulare into spinal column

Basal cell carcinoma presents a relatively low potential and local malignancy and very slow growth giving only occasionally metastatic spreading. The frequency of occurrence of metastatic dissemination is estimated in the literature depending on examined population from 0.028% to 0.55%. Metastases are most often found in lymph nodes, lungs bones and internal organs: liver, spleen, kidneys, adrenal glands, pleura and the peritoneum. Authors present a case of a 69-years old female with an extensive basal cell carcinoma of the head convexity, infiltrating the subcutaneous tissue, periostium, bone and dura mater, giving distant metastases to other bone and soft tissue structures of a thoracic spine, which was confirmed by biopsy and histopathological findings of neoplasm tissue in spine. The primary lesion was successfully treated surgically. Despite administered radiotherapy of metastases in spine, progress of the disease during 1-year period was observed. The patient was alive with metastatic tumours present at last follow-up. Basing on the review of the literature and our case report we can distinguish following factors which may increase the risk of occurrence of basal cell carcinoma metastases: the great extent of the primary lesion, deep penetration to stromal tissue, blood and lymph vessel invasion, long history of tumour occurrence and the presence of metatypia in histopathological findings. The above-mentioned case fulfils the criteria of carcinoma basocellulare metastases proposed by Latters and Kessel and may be included to the general registration list of this cancer in the world.

Experimental study of the effects of different stapling devices in healing of the mechanically sutured bronchial stump

OBJECTIVE

The invention of the mechanical suture of the bronchial stump resulted in the significant decrease of the incidence of bronchial fistulas. Bronchial fistula constitutes the most dangerous complication of the pulmonary resection. In connection with some negative opinions in world literature regarding the safety of applying some types of mechanical suture, the multi-factor analysis of efficacy of bronchial stump closure following the total pneumonectomy by two different types of stapling devices was performed.

METHODS

The experimental study was performed on 22 sheep. Each sheep underwent left pneumonectomy. In group I the bronchus was closed by the hinged-jaw stapling device (TA-Premium, Auto-Suture). In group II the bronchus was closed by the stapling device of parallel pattern (RLV 30 Ethicon). The macroscopic parameters (i.e. linear structure of staples, degree of staples closure, the symmetry of staples closure in the medial and lateral part of bronchial stump) as well as microscopic parameters (i.e. degree of inflammatory reaction, degree disorder in collagen fibers system, degree of disorders in cartilaginous system, degree of vascular proliferation and nervous regeneration) were evaluated.

RESULTS

In three cases of group I the serious abnormalities in staples closure in the medial part of the bronchial stump were revealed. Abnormalities were found also in microscopic evaluation of the specimens. In the whole group the inflammatory reaction predominated in the medial part of bronchial stump near the hinge of the cartridge (P value <0.05). The disorder in the collagen fibers system as well as in the stratified structure of muscular fibers and cartilaginous system was proved. On the other hand, in group II all staples were properly closed in adequate linear structure, without any symmetry in both medial and lateral end of the bronchial stump. The microscopic findings were only the subtle inflammatory process and a slight disarrangement in muscular, collagen and cartilaginous systems.

CONCLUSION

The listed abnormalities of mechanical, hinged-jaw suture of bronchial stump seem to be due to the inaccurate placement of staples, their incomplete closure, and excessive damage to the sutured tissues. We conclude that the application of the hinged-jaw mechanical suture of the bronchial stump might result in higher incidence of bronchial fistula after pneumonectomy.

Perioperative management of a post heart transplantation patient with renal failure qualified to lung resection

Since the first heart transplantation (1967, Christian Bernard), hundreds of similar procedures have been performed all over the world. Considerable advance made in immunosuppressive treatment improved survival rate and long-term efficiency of treatment improved survival rate and long-term efficiency of treatment. Many of these patients suffer from ailments requiring operations which are not connected with the transplanted organ. The present study describes a case of a post heart transplantation patient qualified to lung resection, in whom renal insufficiency occurred in the course of immunosuppressive therapy.

Effects of cyclosporine A on ozone-induced pulmonary lesion formation: pharmacologic elimination of the T-lymphocyte regulatory response

To assess the involvement of T-lymphocytes in ozone-induced lung damage, CD-1 mice were exposed to air or 0.7 ppm ozone (1.37 mg O3/m3 air) in the presence and absence of the immunosuppressive drug cyclosporine A (CSA). Mice were thus divided into four treatment groups for both the 4 and 14 day exposure times: 1) AIR + VEH, 2) AIR + CSA, 3) O3 + VEH, and 4) O3 + CSA. Thy-1.2 positive cells (T-lymphocytes) per pulmonary lesion were determined and quantitative histomorphometric analysis of lesion volume was performed. By Day 14, the number of T-lymphocytes per lesion in O3 + VEH (vehicle) animals had increased to approximately 3.5 times that seen at Day 4. At 4 and 14 days of O3 + CSA treatment, the number of T cells per lesion was half that seen in O3 + VEH mice. At Day 4, lesion size and appearance were comparable in O3 + VEH and O3 + CSA animals, while at Day 14, O3 + CSA treatment resulted in larger and more cellular lesions that contained a greater proportion of polymorphonuclear cells, and the lesions extended further into the lung periphery. Inflammatory cells were observed in areas of epithelial cell proliferation and in alveolar spaces distal to the small airway terminus. After 14 days, lesion volume was approximately twice as great following O3 + CSA administration than with O3 treatment alone. These results are consistent with effects seen in another model of immunosuppression, the nude mouse, and they implicate a regulatory role for T-lymphocytes in the response to ozone.

An immunofluorescence study of T and B lymphocytes in ozone-induced pulmonary lesions in the mouse

Ozone is a photochemical oxidant which reacts with a variety of biological molecules. In experimental animals the toxicity of ozone results from damage to cells in the lung and is associated with the process of reactive repair and an influx of inflammatory cells. In this work we used an indirect immunofluorescence technique to study the effect of ozone on T and B lymphocytes with special reference to their presence in ozone-induced pulmonary lesions. BALB/c mice were exposed to ozone at a concentration of 0.7 ppm for 20 hr per day, 7 days per week, for 4 or 14 days. Control mice were housed in comparable chambers lacking ozone. Frozen sections of lung were prepared and stained for the surface markers Thy-1.2 (T lymphocyte) and sIgM (B lymphocyte). These experiments showed that T lymphocytes infiltrate the lung lesions during ozone inhalation, and increase their presence as ozone exposure continues. They were present in the centroacinar region and tended to occur in clusters within the ozone-induced lesions. In contrast, the infiltration of B lymphocytes was virtually nonexistent with few or no sIgM positive cells present in the lesions after either 4 or 14 days of exposure to ozone. These results show that T lymphocytes occur within the sites of ozone-induced damage and support that this cell type plays a role in the reactive host response to ozone inhalation.

Cellular, biochemical and functional effects of ozone: new research and perspectives on ozone health effects

Ozone, a toxic component of photochemical oxidant air pollution, has been the focus of considerable research efforts for several decades. In spite of this large body of work, questions remain as to the potential risks to human health represented by chronic low-level exposure to ozone. Newer studies in animals have provided fundamental information on the range of biochemical, functional and morphologic responses to ozone exposure. While the response to ozone exposure is extremely complex, some generalities have emerged which may aid attempts to apply the results of these studies to decisions regarding the protection of human health.

Short-term exposure to nitrogen dioxide enhances susceptibility to murine respiratory mycoplasmosis and decreases intrapulmonary killing of Mycoplasma pulmonis

In C57BL/6N and C3H/HeN mice known to be free of all murine pathogens and matched for age, sex, microbiologic, and environmental factors, exposure to NO2 for 4 h prior to exposure to infectious aerosols of Mycoplasma pulmonis resulted in potentiation of murine respiratory mycoplasmosis (MRM). In the C57BL/6N mice, NO2 increased the incidence of death, incidence of gross lung lesions, and incidence of microscopic lung lesions, but did not increase the incidence of infection in the lungs. Nitrogen dioxide affected the C3H/HeN mice (a strain known to be more susceptible than the C57BL/6N strain to MRM) similarly, with the exception that the incidence of death and microscopic lesions were not affected in this strain at the concentrations of M. pulmonis used. Exposure to the oxidant also increased the severity of microscopic lesions and the numbers of Mycoplasma organisms in the lungs of both mouse strains. Thus, NO2 appeared to affect host lung defense mechanisms responsible for limiting the extent of infection. The NO2 exposure level required to produce potentiation varied with the genetic background of the host, the number of Mycoplasma organisms administered, and the end point measured. In further experiments in C57BL/6N mice, exposure to 5 or 10 ppm of NO2 for 4 h prior to infection with aerosolized, radiolabeled M. pulmonis reduced clearance of these organisms from the lungs over a 72-h time period. Nitrogen dioxide exposure did not change the rate of physical removal of Mycoplasma organisms from the lung. Reduced clearance was due to impaired intrapulmonary killing of Mycoplasma organisms in NO2-exposed mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitation of ozone-induced lung lesion density after treatment with an interferon inducer or an anti-interferon antibody

Inhalation of ozone by experimental animals produces activation of lymphocytes in the mediastinal lymph node complex. Both the number and functional reactivity are affected, with evidence of blastic transformation in T cell but not B cell areas of the nodes. In the present work we determine the extent that modulation of a possible product of immune system activation, interferon, is capable of influencing the way that experimental animals respond to zone. Outbred CD-1 mice were treated with an interferon inducer, poly I:C, or with an anti-interferon antibody while being exposed to ozone at a concentration of 0.7 or 0.9 ppm for 20 h per day for 4 days. Interferon induction produced a significant reduction in lesion volumes in both exposure groups, while anti-interferon produced the opposite effect. Less alveolar damage was observed in interferon-induced, ozone-exposed animals than in animals exposed to ozone alone. In contrast, anti-interferon-treated, ozone-exposed animals showed larger lesions which extended to more peripheral structures and were more extensively infiltrated with neutrophilic leukocytes. These results show that interferon induction protects against zone-mediated lung damage. They also suggest that cells are activated during ozone inhalation which mitigate the effects of ozone on the lung by secretion of interferon.

Response of T-cell-deficient mice to ozone exposure

The number, appearance, and functional reactivity of T-lymphocytes of mediastinal lymph nodes are altered during experimental ozone inhalation. The purpose of the present work is to determine how the lymph nodes and lungs of a mutant strain of animal, which lacks this type of cell, differ in their response to ozone exposure when compared with animals that possess a normal complement of lymphocytes. We exposed athymic nude (nu/nu) mice or heterozygous (nu/+) euthymic mice to 0.7 ppm ozone for 20 h/d for 7 or 14 d while maintaining control groups in clean air. At 7 d the lymph-node hyperplastic response normally seen in euthymic, ozone-exposed animals was greatly reduced in exposed athymic animals. By both 7 and 14 d, greater damage had occurred in the lungs of ozone-exposed, athymic animals than in similarly exposed euthymic animals. Lung wet weight divided by body weight, which was used as a general indicator of lung damage, increased by substantially more in athymic animals than in conventional animals. In a parallel manner, quantitative microscopic analysis, a more sensitive indicator, revealed a marked increase in the lung lesion volumes. Qualitative histologic analysis showed that the change in the response in the athymic animal was most prominent in the peripheral region of the lung extending from the alveolar duct to the alveoli, and was characterized by a greater acute inflammatory cell reaction. Possible mechanisms by which the T-cell could produce the observed effect include secretion of factors that enhance inherent resistance of the lung's target cells, or alterations in the way the inflammatory response to ozone-mediated damage occurs. The results support the idea that the mediastinal lymph node lymphocyte response is adaptive in nature and aids in protecting the lung from ozone-mediated effects.

Development of an aerosol model of murine respiratory mycoplasmosis in mice

Animal models of murine respiratory mycoplasmosis due to Mycoplasma pulmonis provide excellent opportunities to study respiratory disease due to an infectious agent. The purpose of the present study was to develop and characterize an aerosol model for the production of murine respiratory mycoplasmosis in mice. The exposure of mice for 30 min to aerosols generated with a DeVilbiss 45 nebulizer in a nose-only inhalation chamber consistently reproduced typical lesions. The chamber was operated with a nebulizer air flow of 5.3 liters/min at 5.0 lb/in and a diluting air flow of 20 liters/min, with the nebulizer containing 5 ml of a suspension of viable M. pulmonis organisms (a concentration between 6 X 10(5) to 6 X 10(10) CFU/ml). Infective aerosol particles of less than a 4.0-micron median aerodynamic diameter with a geometric standard deviation of approximately 2.0 reached the lungs and were evenly distributed among the different lung lobes. A minimum 1.5-log loss of viability in the M. pulmonis suspension was demonstrated. With the exception of the 50% lethal dose, all of the parameters previously established by intranasal inoculation could be examined with the aerosol model. The major advantages of the aerosol model were excellent reproducibility of exposure (both between different experiments and between animals in a given experiment), the avoidance of anesthetization, and the ability to immediately deposit the majority of the organisms in the lung. The only disadvantage was the requirement for large volumes of mycoplasmal cultures.

Strain differences in susceptibility to murine respiratory mycoplasmosis in C57BL/6 and C3H/HeN mice

Not only is murine respiratory mycoplasmosis, due to Mycoplasma pulmonis, a complication of biomedical research, it provides excellent animal models to study the development of a naturally occurring respiratory disease induced by an infectious agent. The understanding of pathogenic mechanisms of disease can be greatly facilitated by studying genetic differences in susceptibility. Five strains of mice with various H-2K haplotypes were examined for their susceptibility to murine respiratory mycoplasmosis; of these, C57BL/6 and C3H/HeN mice were chosen for additional study. There were no significant differences in the incidence of infection in either the upper or lower respiratory tract or in the severity of upper respiratory tract lesions in the two strains as determined at 14 days postinfection. In striking contrast, the C57BL/6 mice were significantly more resistant to the development of gross and microscopic lung lesions and to death due to pneumonia as shown by an almost 100-fold difference in the 50% lethal dose, 50% gross pneumonia dose, and 50% microscopic lesion dose. The most apparent differences in lung lesions between the two strains were in the severity of acute lesions of the bronchial epithelium, the amount of mixed inflammatory response in the alveoli, and the amount of lymphoid infiltrates. All were significantly more severe in C3H/HeN mice. In addition, more C3H/HeN mice developed antibody responses to M. pulmonis. The amount of antibody correlated with lesion severity in both strains.

Differential counts of B and T lymphocytes in the lymph nodes, circulating blood and spleen after inhalation of high concentrations of diesel exhaust

Inhalation of diluted diesel engine exhaust results in the deposition of submicron carbonaceous particles in the respiratory airways. The particles are phagocytized by the pulmonary alveolar macrophages and cleared from the respiratory tract via the mucociliary escalator or through lymphatic channels. Lung clearance via lymphatics results in accumulation of particles in the regional lymph nodes. Differential counts of B and T lymphocytes were performed to determine whether the deposited carbon particles in the lymphatic tissue can alter the subpopulation composition of various lymphoid compartments. In contrast to the effect of materials such as heavy metals, halogenated hydrocarbons or cigarette smoke condensate, all of which have been shown to alter B and T cell differential counts of lymphoid compartments under various test conditions, assays of lymphocytes from tracheobronchial lymph nodes, spleen and blood from guinea pigs exposed to diluted diesel exhaust with a particulate concentration of 1500 micrograms m-3 for up to 8 weeks revealed no significant changes when compared with age-matched controls. Furthermore, cell viability as measured by trypan blue exclusion in the exposed groups was comparable to that of the age-matched controls. These data indicate that, within the range of tested conditions, the deposited diesel particles do not exert major effects on the parameters of the immune system that were measured.