Inflammation and tissue damage in mouse lung by single and repeated dosing of urban air coarse and fine particles collected from six European cities.

The authors have previously demonstrated heterogeneities in the inflammatory activities of urban air fine (PM(2.5-0.2)) and coarse (PM(10-2.5)) particulate samples collected from six European cities with contrasting air pollution situations. The same samples (10 mg/kg) were intratracheally instilled to healthy C57BL/6J mice either once or repeatedly on days 1, 3, and 6 of the study week. The lungs were lavaged 24 h after the single dose or after the last repeated dosing. In both size ranges, repeated dosing of particles increased the total cell number in bronchoalveolar lavage fluid (BALF) more than the respective single dose, whereas cytokine concentrations were lower after repeated dosing. The lactate dehydrogenase (LDH) responses increased up to 2-fold after repeated dosing of PM(2.5-0.2) samples and up to 6-fold after repeated dosing of PM(10-2.5) samples. PM(10-2.5) samples evoked a more extensive interstitial inflammation in the mouse lungs. The constituents with major contributions to the inflammatory responses were oxidized organic compounds and transition metals in PM(2.5-0.2) samples, Cu and soil minerals in PM(10-2.5) samples, and Zn in both size ranges. In contrast, poor biomass and coal combustion were associated with elevated levels of polycyclic aromatic hydrocarbons (PAHs) and a consistent inhibitory effect on the inflammatory activity of PM(2.5-0.2) samples. In conclusion, repeated intratracheal instillation of both fine and coarse particulate samples evoked enhanced pulmonary inflammation and cytotoxicity compared to single-dose administration. The sources and constituents of urban air particles responsible for these effects appear to be similar to those encountered in the authors' previous single-dose study.

Subchronic inhalation of mixtures of cigarette smoke constituents in Xpa-/-p53+/- knock-out mice: a comparison of intermittent with semi-continuous exposure to acetaldehyde, formaldehyde, and acrolein.

We investigated whether inhaling peak concentrations of aldehydes several times daily is more damaging than semi-continuously inhaling low-dose aldehydes. We exposed Xpa-/-p53+/- knock-out mice either intermittently or semi-continuously to mixed acetaldehyde, formaldehyde, and acrolein. The intermittent regimen entailed exposure to the aldehydes 7 min every 45 min, 12 times/day, 5 days/week, corresponding to concentrations inhaled by smokers. Semi-continuously exposed animals received half the dose of aldehydes in 8h/day, 5 days/week. Some mice in each group were sacrificed after 13 weeks of exposure; the rest breathed clean air until the end of 1 year. Mice injected intratracheally with benzo[a]pyrene formed a positive control group. The nasal cavity, lungs, and any macroscopically abnormal organs of all mice were analysed histopathologically. After 13 weeks of exposure, the subacute, overall, histopathological changes induced by the inhalation differed noticeably between the intermittently and semi-continuously treated Xpa-/-p53+/- knock-out mice. After 13 weeks of mixed aldehyde exposure, atrophy of the olfactory epithelium generally appeared, but disappeared after 1 year (adaptation and/or recovery). Respiratory epithelial metaplasia of the olfactory epithelium occurred at a higher incidence at 1 year. Except for a significantly greater number of tumours observed in knock-out mice compared to wild mice (semi-continuous aldehyde exposure and controls), no differences between the semi-continuous and intermittent exposure groups were observed.

Antitumor effect, cardiotoxicity, and nephrotoxicity of doxorubicin in the IgM solid immunocytoma-bearing LOU/M/WSL rat.

Antitumor activity, cardiotoxicity, and nephrotoxicity induced by doxorubicin were studied in LOU/M/WSL inbred rats each bearing a transplantable solid IgM immunocytoma. Animals with a tumor (diameter, 15.8 +/- 3.3 mm) were treated with iv injections of doxorubicin on 5 consecutive days, followed by 1 weekly injection for 7 weeks (dose range, 0.015-4.0 mg/kg body wt). Tumor regression was observed with 0.5 mg doxorubicin/kg. Complete disappearance of the tumor was induced with 1.0 mg doxorubicin/kg. Histologic evidence of cardiotoxicity scored as grade III was only observed at a dose of 1.0 mg doxorubicin/kg. Light microscopic evidence of renal damage was seen above a dose of 0.5 mg doxorubicin/kg, which resulted in albuminuria and very low serum albumin levels. In the group that received 1.0 mg doxorubicin/kg, the serum albumin level decreased from 33.6 +/- 4.1 to 1.5 +/- 0.5 g/liter. Ascites and hydrothorax were observed simultaneously. The same experiments were performed with non-tumor-bearing rats, in which no major differences were observed. In conclusion, antitumor activity, cardiotoxicity, and nephrotoxicity were studied simultaneously in the same LOU/M/WSL rat. Albuminuria due to renal damage led to extremely low serum albumin levels, so ascites and hydrothorax were not necessarily a consequence of the observed cardiomyopathy.

Time-course study on doxorubicin-induced nephropathy and cardiomyopathy in male and female LOU/M/Wsl rats: lack of evidence for a causal relationship.

In a previous study on doxorubicin-induced cardiotoxicity in LOU/M/Wsl rats, severe nephropathy has been observed; therefore, the question was raised whether nephropathy adds to or even might be responsible for doxorubicin-induced cardiomyopathy in rats. For elucidation of this question, the temporal relationship between the onset of doxorubicin-induced cardiomyopathy and nephropathy was studied. In addition, examination was made of whether modifications of the treatment schedule could circumvent nephrotoxicity. Because preliminary studies had shown that female LOU/M/Wsl rats developed less doxorubicin-induced albuminuria, both male and female LOU/M/Wsl rats were treated with an iv dose of 1 mg doxorubicin/kg (body wt)/rat on five consecutive days and then weekly. Saline-treated animals served as controls. Albuminuria, serum albumin, and serum creatine levels were assessed weekly. For histologic examination, 5 male and 5 female rats were killed weekly. At day 14 and thereafter, doxorubicin-treated male rats showed albuminuria greater than or equal to 10 g/liter. Albuminuria of greater than or equal to 10 g/liter was not avoided by modifications of the treatment schedule. Female rats had on day 14 a urinary albumin level of 1.0-3.0 g/liter, yet reaching the level of greater than or equal to 10 g/liter at day 49. In male rats serum albumin levels decreased to levels below 10 g/liter (p less than .001 vs. finding for day 0); in contrast female rats maintained constant serum albumin levels till day 49. Serum creatine levels showed a tendency to rise, the values of male rats not being measured after day 28 due to hyperlipidemia; the levels of female rats increased from 37.8 +/- 3.0 mumol/liter to 53.7 +/- 2.5 mumol/liter on day 49 (P less than .001). At day 10 in male and female rats a grade 1-1.5 cardiomyopathy score, assessed according to the modified Billingham scoring system, was found, gradually increasing to grade 2.5-3 cardiomyopathy, both in males and females, on day 49. In male LOU/M rats the nephropathy developed steadily from day 14 and thereafter, whereas in females the rate of development of kidney damage was slower and at the end point of the study the severity of kidney lesions was less in comparison to that of the males. The onset of cardiomyopathy and nephropathy was simultaneous. It was concluded that cardiomyopathy observed in LOU/M rats is a phenomenon independent of nephropathy.

Failure of the antioxidant vitamin E to protect against adriamycin-induced cardiotoxicity in the rabbit.

Recently, vitamin E has been proposed to protect against Adriamycin-induced cardiotoxicity. We studied contractile decline and ultramicroscopic alterations of the heart of rabbits chronically treated with Adriamycin up to a cumulative dose of 400 mg/sq m. High doses of vitamin E did not protect against the Adriamycin-induced development of severe contractile decline as evaluated by means of measurement of the interval-force relationship curve. Light and electron microscopic analysis did not show any signs of protection against Adriamycin-induced morphological alterations. Biochemical and hematological alterations. Biochemical and hematological alterations caused by the antineoplastic agent were similar in both Adriamycin-treated animal groups. Coadministration of vitamin E did result in an increased life span. This study indicates that vitamin E does not protect against the development of cardiomyopathy and contractile decline after chronic exposure to Adriamycin.

Evidence for a diminished maturation of preosteoblasts into osteoblasts during aging in rats: an ultrastructural analysis.

Bone is subject to continuous remodeling throughout life. The age-related loss of (trabecular) bone, leading to senile osteopenia, is mainly due to impaired bone formation. Osteoblasts (OB) and osteoclasts (OC) have been identified as playing a crucial role in the process of bone turnover, but the contribution made by their precursors is not well documented. We analyzed the cells of the osteoblast and osteoclast cell lineage along the trabecular bone of tibiae and the stromal cells in the marrow of aging BN/Bi Rij rats using electron microscopy. It appeared possible to distinguish preosteoblasts (pre-OB), OB, preosteoclasts (pre-OC), OC, and inactive bone-lining cells. Periods of increase, the maximal peak, and the decrease in trabecular bone volume were defined by means of morphometric measurements of trabecular bone volume. We found a decrease of more than 10-fold in the number of OB with age, but the numbers of pre-OB, pre-OC, and OC expressed per unit bone length, although variable, were age independent. The relative bone resorption and formation surface, expressed as a percentage of the total bone surface, decreased 2- and 15-fold, respectively. In 2-year-old animals the total volume of stromal cells, part of which constitutes the stem cell compartment of the osteogenic lineage, was a quarter of that found in 1-month-old animals and a third of that found in 6-month-old animals. The loss of trabecular bone is concomitant with a sharp increase in the ratio of pre-OB/OB, the ratio of OC/OB, and in the ratio of resorption to formation surfaces. There was no relation between the ratio of pre-OC/OC with age. These data lead to the conclusion that the main factor causing bone loss with age is a diminished maturation of pre-OB into OB.

A rat cytomegalovirus infection model as a tool for immunotoxicity testing.

A rat cytomegalovirus infection model for use in immunotoxicity testing has been developed. In resistance against viruses, natural killer cells and cytotoxic T-cells play an important role. Therefore, this model complements other rat host resistance models for immunotoxicity testing, i.e. existing bacterial and parasitic infection models in which cytotoxic T-cells and natural killer cells play a minor role. Host resistance against cytomegalovirus infections in the rat was determined by titrating infectious virus levels in organs after cytomegalovirus infection in an in vitro infectivity test denoted as the Plaque Forming Unit (PFU) Test. In this test, homogenates of different organs were investigated for infectious virus titers on rat embryonic cell monolayers. We demonstrated that in the salivary gland, the major target organ for rat cytomegalovirus, virus was detectable from 8 days onward after intraperitoneal infection. To show that this model is suitable for the detection of immunotoxicity four different methods for immunosuppression were investigated: 1. gamma-irradiation, 2. congenitally athymic rats, 3. chemically induced immunosuppression, 4. ultraviolet-B (UVB) irradiation. Rat cytomegalovirus titers in the salivary glands of irradiated (500 rad 1 day prior to infection) or congenitally athymic rats were significantly increased as compared to non-irradiated rats and euthymic control rats respectively. In TOX-Wistar rats, given 20 or 80 mg bis(tri-n-butyltin)oxide (TBTO) per kg food beginning 6 weeks before cytomegalovirus infection, a regimen known to have immunotoxic effects, cytomegalovirus titers in the salivary glands were significantly increased as compared to non-TBTO-treated cytomegalovirus infected rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in neuroreceptor function of tracheal smooth muscle following acute ozone exposure of guinea pigs.

We studied the effect of in vivo ozone inhalation (3 ppm, 2 h) on neuroreceptor function in guinea pig tracheal smooth muscle in vitro and the role of the epithelial layer in this process. Changes in smooth muscle tension after stimulation of the muscarinic- and beta-adrenergic receptor were recorded isometrically and stained tracheal tissue sections were histologically evaluated for changes in the epithelial and smooth muscle layer. Ozone exposure resulted in an increase in maximal contraction following stimulation of the muscarinic receptor, whereas pD2 values remained unchanged. After stimulation of the beta-adrenergic receptor no increase in maximal relaxation but only an increase in pD2 value was observed after correction for differences in precontraction level in control- and ozone-exposed situations. Mechanical removal of the epithelial layer resulted in a slight increase of the maximal contraction level after stimulation with methacholine in the control situation, whereas exposure to ozone resulted in a strong decrease of the maximal contraction level under these conditions. Histological stainings showed a slight and focal influx of neutrophilic granulocytes in the epithelial layer, submucosal layer and airway lumen after exposure to ozone. These data support the idea that ozone is able to increase the maximal degree of airway narrowing upon muscarinergic stimulation, i.e. a hyperreactivity response. The results also suggest that functionally altered epithelium plays an important role in the process of ozone-induced hyperreactivity, possibly linked with an early inflammatory response.

Adjuvant activity of various diesel exhaust and ambient particles in two allergic models.

In the framework of an EU study entitled "Respiratory Allergy and Inflammation Due to Ambient Particles" (RAIAP), various collected particulate matter samples were to be tested for their adjuvant potency in two animal models of allergy. A pollen allergy model in the Brown Norway (BN) rat and an ovalbumin model in the BALB/c mouse were used in this study to compare the discriminatory value of these two models and to evaluate them for later studies of collected RAIAP-samples. Two different sources of diesel exhaust particles (DEP I and DEP II ), a residual oil fly ash source (ROFA), and two sources of ambient particles (Ottawa dust, EHC-93, and road tunnel dust, RTD) were tested. Rats were sensitized intratracheally with Timothy grass pollen (Phleum pratense, 200 microl, 10 mg/ml) on d 0, challenged on d 21, and examined on d 25. Mice were sensitized intranasally at d 0 and 14, challenged intranasally at d 35, 38, and 41 (50 microl, 0.4 mg ovalbumin/ml), and examined at d 42. Particulate matter (PM) was administered either during the sensitization phase only or during the sensitization and challenge phases (for mice only) or during the challenge phase only. In the pollen model, only DEP I, but not DEP II, ROFA, EHC-93, and RTD, stimulated the immunoglobulin (Ig) E and IgG1 response in serum to pollen allergens. In addition to this adjuvant effect noted, no other biomarkers in lung or bronchoalveolar lavage (BAL) revealed adjuvant activity in the pollen model. In the BAL of BN rats exposed to a combination of pollen and PM, the percentages of eosinophilic granulocytes were decreased compared to the BAL of BN rats immunized with pollen only. In the ovalbumin model, the IgE levels in serum were increased in mice after coexposure to ovalbumin and PM (including DEPI, DEPII, ROFA, EHC-93, and RTD) in the sensitization phase but not after coexposure during the challenge phase only. The inflammatory response was greater in the lung, predominantly the influx of eosinophilic granulocytes, as was observed by both histopathological examination and BAL analysis. In addition, BAL levels of inflammatory interleukin (IL)-4 were increased. Based on the IgE antibody response to ovalbumin, the ovalbumin model ranked the adjuvant capacity of the particles in the following order: RTD > ROFA > EHC-93 > DEPI > DEPII. In conclusion, the ovalbumin model is a sensitive system to detect adjuvant activity of airborne particles, whereas the pollen-induced allergy model in rat was less sensitive.

No beneficial effect of N-acetylcysteine treatment on broncho-alveolar lavage fluid variables in acute nitrogen dioxide intoxicated rats.

1. In previous studies a rat inhalation model was developed to investigate the efficacy of treatment in acute NO2 intoxication. 2. N-acetylcysteine (NAC) was administered intravenously to study its effect on biochemical variables in broncho-alveolar lavage fluid in acute NO2 intoxicated rats. It was decided to start the intravenous administration of NAC 24 h before the exposure to NO2 to induce higher intracellular glutathione (GSH) levels in lung cells of NAC-treated rats compared to not NAC-treated rats. Because, on theoretical grounds, the therapeutic effect of NAC may be expected to be especially marked during the first 24 h after exposure, the rats were observed for a period of 24 h and were then killed for investigation. A loading dose of 85 mg kg-1 h-1 or 170 mg kg-1 h-1 was followed by a continuous infusion (until autopsy) with a dose of 225 mg kg-1 24 h-1 or 450 mg kg-1 24 h-1 respectively. 3. Twenty four hours after exposure to 175 ppm NO2 (1 ppm is 1.88 mg m-3) for 10 min, NAC did not reduce the increase of variables in broncho-alveolar lavage fluid which reflect the severity of lung damage. 4. The protein and albumin concentration and the activities of angiotensin converting enzyme and alkaline phosphatase in broncho-alveolar lavage fluid after NO2 exposure were even more increased in the NAC-treated than in the saline-treated rats, but none of the differences was statistically significant. 5. In sham exposed rats no effect of NAC was observed.

Desferrioxamine treatment reduces histological evidence of lung damage in rats after acute nitrogen dioxide (NO2) intoxication.

1. In previous studies a rat inhalation model was developed to investigate the efficacy of treatment in acute NO2 intoxication. 2. Desferrioxamine was administered intravenously to study its effect on histological alterations in lung tissue in rats after acute NO2 exposure. 3. Twenty four hours after exposure to 175 ppm NO2 for 10 minutes the lung injury observed by light microscopy in the desferrioxamine treated rats was less pronounced than in the saline treated rats. 4. Desferrioxamine appeared to provide more protection with a dose of 100 mg kg-1 24 h-1 than with 200 mg kg-1 24 h-1.

Rat model to investigate the treatment of acute nitrogen dioxide intoxication.

1. The pulmonary toxic events induced by acute nitrogen dioxide (NO)2 exposure were studied in the rat to develop an inhalation model to investigate therapeutic measures. 2. A good correlation was observed between the lung weights and severity of the atypical pneumonitis. The pulmonary effects observed, became more pronounced with increasing NO2 concentrations (0, 25, 75, 125, 175 or 200 ppm, 1 ppm NO2 = 1.88 mg m-3 NO2) and exposure times (5, 10, 20 or 30 min). 3. An adequate NO2 concentration is 175 ppm, because it can induce a severe lung injury without mortality. This makes it possible to investigate suitable therapeutic interventions for several days. 4. Following acute inhalatory NO2 intoxication, transformation of NO2 to nitrate is presumably more notable than transformation to nitrite. 5. The transformation of NO2 to nitrate in lung tissue causes a slight increase in the serum nitrite concentration, which does not induce measurable formation of methaemoglobin. 6. Presumably, methaemoglobin does not contribute to the toxicity of NO2 intoxication.

Biochemical and histological alterations in rats after acute nitrogen dioxide intoxication.

1. In previous studies a rat inhalation model was developed to investigate the treatment of acute nitrogen dioxide (NO2) intoxication. 2. Biochemical parameters, which may be important for the evaluation of lung injury and repair, were reviewed and compared with the histology. 3. After exposure to high NO2 concentrations (75 ppm, 125 ppm or 175 for 10 min) the lung injury observed by light microscope was most pronounced after 24 h and became worse with increasing concentration. 4. The most sensitive indicators for lung injury in the broncho-alveolar lavage fluid (BAL) were protein and albumin concentrations, angiotensin converting enzyme activity, beta-glucuronidase activity and the presence of neutrophil leucocytes. The changes observed in these variables were dose-dependent. Following exposure to 175 ppm the protein and albumin concentrations and the angiotensin converting enzyme activity showed a 100-fold increase, while the beta-glucuronidase activity showed a 10-fold increase. 5. Glucose-6-phosphate dehydrogenase and glutathione peroxidase in the supernatant of lung homogenate and gamma-glutamyl transferase activity in BAL are likely to be the most practical parameters for monitoring the phase of repair because their activities were maximal at the moment histological changes were reduced in intensity. 6. Repair was almost complete 7 d following exposure.

Development of a rabbit model to investigate the effects of acute nitrogen dioxide intoxication.

1. In previous studies a rat inhalation model was developed to investigate the effects of intervention after acute NO2 exposure. The object of the present study was to investigate whether acute NO2 intoxication induced comparable effects in rabbits as it does in rats. Where the effects of intervention in both species are similar, then the conclusions drawn from these studies may have more relevance for the treatment of man. 2. Biochemical variables in bronchoalveolar lavage and supernatant from lung homogenate, which may be relevant for the evaluation of lung injury and repair, were investigated and compared with histology. 3. After NO2 exposure for 10 min, the pulmonary effects observed became more pronounced with increasing NO2 concentrations (0, 125, 175, 250, 400, 600 or 800 ppm) [1 ppm NO2 is 1.88 mg m-3]. The effects in rabbits were found to be broadly comparable with those in rats. 4. To achieve severe lung injury in rabbits without mortality, enabling investigations of the effects of intervention over several days, exposure to a NO2 concentration of 600 ppm for 10 min was most appropriate, while a concentration of 175 ppm NO2 was needed to attain comparable effects in rats. 5. The repair phase starts later, namely at 3 days after exposure in rats, compared to 5 days in rabbits.

Nasal lavage as tool for health effect assessment of photochemical air pollution.

It is widely accepted that humans exposed to known concentrations of ozone under controlled conditions exhibit reversible changes that affect the large and small airways as well as the alveolar region of the lung. Among the reversible changes, the induction of inflammatory responses in the lung are of major concern. Many of the cell types found in the lining of the nasopharyngeal region are similar to cells of the tracheal and bronchial lining. therefore, it has been suggested that the cellular responses in the nose to toxicants are likely to be similar to the lower airway at the same dose of the agent. If these pollutants are respiratory irritants, capable of causing cellular damage, effects may therefore be detected in the nasal passage. Experimental studies have shown that the inflammatory response in the nose may be predictive for the situation in the lung. In this paper we described the results of a feasibility study on the use of nasal lavage for epidemiological studies. Nasal lavages were performed in 12 volunteers, 5-7 times per volunteer during 2 months. Polymorph nuclear leukocytes (PMN's), immune mediators and markers for exudation were monitored in the nasal lavage (NAL). It was found that the procedure of the nasal lavage technique was minimally invasive, very well tolerated and no adverse side effect were observed. The leukocytes, the proteins myeloperoxidase (MPO), eosinophil cationic proteins myeloperoxidase (MPO), eosinophil cationic protein (ECP) and interleukin-8 (IL-8) were detectable in NAL of most volunteers, while tryptase IgE and IL-6 were not detectable. Exudation markers albumin, urea and uric acid were also detectable. The coefficient of variance (CV) values of the various cells and mediators varied between 13% and 137%. It was calculated that, except for the number of leukocytes and the concentration of ECP, it should be possible to detect ozone effects with a study-protocol of 6 repeated measurements among 35 children and an assumed 26% increase in cells or mediators per 100 micrograms O3 per m3. To measure increase in leukocytes number or in ECP concentration more children are needed. In conclusion, this pilot study has shown that it is possible to measure relevant biomarkers in NAL, and that these assays can be easily incorporated in epidemiological studies.

Host genetics of Bordetella pertussis infection in mice: significance of Toll-like receptor 4 in genetic susceptibility and pathobiology.

The susceptibility to and the severity of Bordetella pertussis infections in infants and children varies widely, suggesting that genetic differences between individuals influence the course of infection. We have previously identified three novel loci that influence the severity of whooping cough by using recombinant congenic strains of mice: Bordetella pertussis susceptibility loci 1, 2, and 3 (Bps1, -2, and -3). Because these loci could not account for all genetic differences between mice, we extended our search for additional susceptibility loci. We therefore screened 11 inbred strains of mice for susceptibility to a pertussis infection after intranasal infection. Susceptibility was defined by the number of bacteria in the lungs, being indicative of the effect between the clearance and replication of bacteria. The most resistant (A/J) and the most susceptible (C3H/HeJ) strains were selected for further genetic and phenotypic characterization. The link between bacterial clearance and chromosomal location was investigated with 300 F2 mice, generated by crossing A/J and C3H/HeJ mice. We found a link between the delayed clearance of bacteria from the lung and a large part of chromosome 4 in F2 mice with a maximum log of the odds score of 33.6 at 65.4 Mb, which is the location of Tlr4. C3H/HeJ mice carry a functional mutation in the intracellular domain of Tlr4. This locus accounted for all detectable genetic differences between these strains. Compared to A/J mice, C3H/HeJ mice showed a delayed clearance of bacteria from the lung, a higher relative lung weight, and increased body weight loss. Splenocytes from infected C3H/HeJ mice produced almost no interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) upon ex vivo restimulation with B. pertussis compared to A/J mice and also showed a delayed gamma interferon (IFN-gamma) production. TNF-alpha expression in the lungs 3 days after infection was increased fivefold compared to uninfected controls in A/J mice and was not affected in C3H/HeJ mice. In conclusion, Tlr4 is a major host factor explaining the differences in the course of infection between these inbred strains of mice. Functional Tlr4 is essential for an efficient IL-1-beta, TNF-alpha, and IFN-gamma response; efficient clearance of bacteria from the lung; and reduced lung pathology.

Dose dependency of adjuvant activity of particulate matter from five European sites in three seasons in an ovalbumin-mouse model.

Various particulate matter (PM) samples were tested for their adjuvant potency in an animal model of allergy (ovalbumin) in the European Union study entitled Respiratory Allergy and Inflammation Due to Ambient Particles. Coarse and fine ambient particles were collected during spring, summer, and winter in Rome, Oslo, Lodz, Amsterdam, and De Zilk. De Zilk, at the Dutch seaside, has mainly westerly winds and served as a negative pollution control. EHC-93 (Ottawa dust) was used as a positive control. We studied the adjuvant potency of the particle antibody responses to ovalbumin and histopathological changes in the lung. After a sensitization phase by coexposure to EHC-93 and ovalbumin, the antibody response to ovalbumin and inflammatory responses in the lung were huge. There was more adjuvant activity in reaction to 9-mg/ml samples than to 3-mg/ml samples. A best-fit analysis of these samples shows that the ambient coarse and fine particles at these sites, in combination with allergens, have severe to mild adjuvant activity in the order Lodz, Rome, Oslo, and Amsterdam. A high dose of the fine fraction was more potent than a high dose of the coarse fraction, except at De Zilk, where the reverse was true. Spring and winter PM was more potent than summer PM. Depending on the site, either a water-soluble or a water-insoluble fraction was responsible for the adjuvant activity. A concentration of 3 mg/ml is effective for screening high-activity samples, as is a concentration of 9 mg/ml for screening low-activity samples in the ovalbumin-mouse model.

Application of the disector method in the light microscopic quantification of type II pneumocytes in control and ozone-exposed rats.

Alveolar type II cells in control and ozone-exposed rat lungs were counted at the light microscopical level with the 'disector method'. The type II cells were unequivocally marked by histochemical staining for alkaline phosphatase activity in 2 microns plastic sections. By this counting method, the mean number of type II cells per lung in control rats was of the same magnitude as those reported in the literature, using point counting methods. After exposure of rats to 1.6 mg ozone/m3 for 7 days, a 50% increase in the mean number of type II cells was observed. The use of the disector method at the light microscopical level offers some advantages above a quantification at the electron microscopical level. The procedure is less time-consuming, larger areas can be screened, two parallel countings can be performed in one set of sections and there is no need for an exact knowledge about the diameter of the measured particle.

An experimental study on the morphogenesis of spina bifida.

This investigation was performed to study the morphogenesis of caudal meningomyeloschisis or spina bifida aperta during neurulation. Pregnant rats were treated wih trypan blue to induce these defects in the closure of the neural walls. Maternal serum was studied to determine trypan blue levels. Both control and treated embryos were examined grossly, at cellular and subcellular level on days 10 through 13 of gestation. Trypan blue was distributed throughout the maternal tissues. There existed a maternal blood-brain barrier and a barrier at the level of the visceral yolk sac and embryonic gut preventing passage of the dye through these entodermal structures. The interstitial space in the paraxial mesenchyme was considerably increased in day 10 treated embryos (6--7 somites) but cellular and ultrastructural changes were not seen. This accumulation of intercellular fluid was only seen in the restricted area of the mesoderm above the invaginating intra-embryonic entoderm. On day 11 the closure of the neural walls was completed in control embryos. In the treated embryos of the similar stages a blister which contained embryonic blood cells had replaced the interstitial mesenchymal fluid. This structural disturbance in the non-segmented mesenchyme interfered primarily with the neurulation and resulted in caudal meningomyeloschisis (spina bifida aperta). Trypan blue was thought to interfere with the function of the extra-embryonic membranes and the primitive gut. The results of this study supported the hypothesis of indirect teratogenic effect upon the embryo.