Sub-chronic inhalation of lead oxide nanoparticles revealed their broad distribution and tissue-specific subcellular localization in target organs.

BACKGROUND: Lead is well known environmental pollutant, which can cause toxic effects in multiple organ systems. However, the influence of lead oxide nanoparticles, frequently emitted to the environment by high temperature technological processes, is still concealed. Therefore, we investigate lead oxide nanoparticle distribution through the body upon their entry into lungs and determine the microscopic and ultramicroscopic changes caused by the nanoparticles in primary and secondary target organs. METHODS: Adult female mice (ICR strain) were continuously exposed to lead oxide nanoparticles (PbO-NPs) with an average concentration approximately 106 particles/cm3 for 6 weeks (24 h/day, 7 days/week). At the end of the exposure period, lung, brain, liver, kidney, spleen, and blood were collected for chemical, histological, immunohistochemical and electron microscopic analyses. RESULTS: Lead content was found to be the highest in the kidney and lungs, followed by the liver and spleen; the smallest content of lead was found in brain. Nanoparticles were located in all analysed tissues and their highest number was found in the lung and liver. Kidney, spleen and brain contained lower number of nanoparticles, being about the same in all three organs. Lungs of animals exposed to lead oxide nanoparticles exhibited hyperaemia, small areas of atelectasis, alveolar emphysema, focal acute catarrhal bronchiolitis and also haemostasis with presence of siderophages in some animals. Nanoparticles were located in phagosomes or formed clusters within cytoplasmic vesicles. In the liver, lead oxide nanoparticle exposure caused hepatic remodeling with enlargement and hydropic degeneration of hepatocytes, centrilobular hypertrophy of hepatocytes with karyomegaly, areas of hepatic necrosis, occasional periportal inflammation, and extensive accumulation of lipid droplets. Nanoparticles were accumulated within mitochondria and peroxisomes forming aggregates enveloped by an electron-dense mitochondrial matrix. Only in some kidney samples, we observed areas of inflammatory infiltrates around renal corpuscles, tubules or vessels in the cortex. Lead oxide nanoparticles were dispersed in the cytoplasm, but not within cell organelles. There were no significant morphological changes in the spleen as a secondary target organ. Thus, pathological changes correlated with the amount of nanoparticles found in cells rather than with the concentration of lead in a given organ. CONCLUSIONS: Sub-chronic exposure to lead oxide nanoparticles has profound negative effects at both cellular and tissue levels. Notably, the fate and arrangement of lead oxide nanoparticles were dependent on the type of organs.

Determinants of the prevalence of Heligmosomum costellatum (Heligmosomidae: Trichostrongyloidea) in a common vole population in southern Moravia, Czech Republic.

A study of nematode (Heligmosomum costellatum) prevalence in the common vole (Microtus arvalis) population was performed in 2002 and 2003 in an agricultural region of southern Moravia, Czech Republic. The influence of the trapping date, body weight, age, gender and reproduction of the common vole on the prevalence of the larvae of H. costellatum encapsulated in the stomach wall was examined. Of 503 common voles examined, 27.6% were H. costellatum positive. The prevalence of H. costellatum in the common vole population was influenced mainly by the weight, trapping date, year and reproductive state, as well as by the interactions between year and gender and between year and reproductive state. The influence of age was weak. The most infected common vole groups were the older, heavier and already reproducing females captured from April to August and all voles captured in 2002. In general, parasite prevalence seems to be dependent on the population parameters of the host species. However, the H. costellatum prevalence study in a single common vole population was not sufficient to fully describe and explain the nematode-host interactions.

Severe granulomatous lesions in several organs from Eustrongylides larvae in a free-ranging dice snake, Natrix tessellata.

During an extensive study regarding the epidemiology of larval Eustrongylides infestation in a free-ranging endangered population of dice snakes (Natrix tessellata) from Histria, Romania, an adult female was euthanized to evaluate pathologic changes. Parasites appeared as nodules at various locations: in subcutaneous connective tissues, on the serosae of the intestines and liver. Histologic sections revealed nematode larvae surrounded by a capsule, forming a parasitic granuloma with 3 layers: macrophage layer, lymphocyte layer, and fibrous capsule. Differences between newly formed and mature granulomas consisted mainly in the eosinophilic infiltration. Other types of parasitic granulomas of reptiles are discussed in comparison with our findings.

Multimammate rat (Mastomys natalensis), Tristram's jird (Meriones tristrami) and Wagner's gerbil (Gerbillus dasyurus) as laboratory models of acute neosporosis.

To test the different sensitivity of rodents of the subfamily Murinae and Gerbillinae, Wagner's gerbils (Gerbillus dasyurus), Tristram's jirds (Meriones tristrami) and multimammate rats (Mastomys natalensis) were inoculated with Neospora caninum tachyzoites. Clinical signs of neosporosis appeared in all inoculated animals. Histopathological examination confirmed the presence of tachyzoites in brains, lungs, skeletal muscle, myocardium, liver, in serosa of stomach and intestines, and in vesicular accessory genital glands. An examination of brains by PCR revealed presence of N. caninum DNA in all experimentally N. caninum infected rodents. The susceptibility of Wagner's gerbils and Tristram's jirds further proved the high sensitivity of gerbiline rodents to the N. caninum infection. The finding of N. caninum tachyzoites in the vesicular accessory genital glands of the infected gerbils suggests the usefulness of the rodent model for demonstration of N. caninum in the male reproductive system. Moreover, the multimammate rat was a susceptible experimental host to be the first immunocompetent rodent of the subfamily Murinae.