Impact of acute and subchronic inhalation exposure to PbO nanoparticles on mice.

Lead nanoparticles (NPs) are released into air from metal processing, road transport or combustion processes. Inhalation exposure is therefore very likely to occur. However, even though the effects of bulk lead are well known, there is limited knowledge regarding impact of Pb NPs inhalation. This study focused on acute and subchronic exposures to lead oxide nanoparticles (PbO NPs). Mice were exposed to PbO NPs in whole body inhalation chambers for 4-72 h in acute experiment (4.05 × 106 PbO NPs/cm3), and for 1-11 weeks in subchronic experiment (3.83 × 105 particles/cm3 in lower and 1.93 × 106 particles/cm3 in higher exposure group). Presence of NPs was confirmed in all studied organs, including brain, which is very important considering lead neurotoxicity. Lead concentration gradually increased in all tissues depending on the exposure concentration and duration. The most burdened organs were lung and kidney, however liver and brain also showed significant increase of lead concentration during exposure. Histological analysis documented numerous morphological alterations and tissue damage, mainly in lung, but also in liver. Mild pathological changes were observed also in kidney and brain. Levels of glutathione (reduced and oxidized) were modulated mainly in lung in both, acute and subchronic exposures. Increase of lipid peroxidation was observed in kidney after acute exposure. This study characterized impacts of short to longer-term inhalation exposure, proved transport of PbO NPs to secondary organs, documented time and concentration dependent gradual increase of Pb concentration and histopathological damage in tissues.

Impact of acute and chronic inhalation exposure to CdO nanoparticles on mice.

Cadmium nanoparticles can represent a risk in both industrial and environmental settings, but there is little knowledge on the impacts of their inhalation, especially concerning longer-term exposures. In this study, mice were exposed to cadmium oxide (CdO) nanoparticles in whole body inhalation chambers for 4 to 72 h in acute and 1 to 13 weeks (24 h/day, 7 days/week) in chronic exposure to investigate the dynamics of nanoparticle uptake and effects. In the acute experiment, mice were exposed to 2.95 × 106 particles/cm3 (31.7 µg CdO/m3). The same concentration and a lower one (1.18 × 106 particles/cm3, 12.7 µg CdO/m3) were used for the chronic exposure. Transmission electron microscopy documented distribution of nanoparticles into all studied organs. Major portion of nanoparticles was retained in the lung, but longer exposure led to a greater relative redistribution into secondary organs, namely the kidney, and also the liver and spleen. Accumulation of Cd in the lung and liver occurred already after 24 h and in the brain, kidney, and spleen after 72 h of exposure, and a further increase of Cd levels was observed throughout the chronic exposure. There were significant differences in both Cd accumulation and effects between the two exposure doses. Lung weight in the higher exposure group increased up to 2-fold compared to the control. Histological analyses showed dose-dependent alterations in lung and liver morphology and damage to their tissue. Modulation of oxidative stress parameters including glutathione levels and increased lipid peroxidation occurred mainly after the greater chronic exposure. The results emphasize risk of longer-term inhalation of cadmium nanoparticles, since adverse effects occurring after shorter exposures gradually progressed with a longer exposure duration.

Simultaneous determination of reduced and oxidized glutathione in tissues by a novel liquid chromatography-mass spectrometry method: application in an inhalation study of Cd nanoparticles.

The paper presents the development of an advanced extraction and fast analytical LC MS/MS method for simultaneous analyses of reduced and oxidized glutathione (GSH and GSSG, respectively) in different animal tissues. The simultaneous determination of GSH and GSSG is crucial because the amount and ratio of both GSH and GSSG may be altered in response to oxidative stress, an important mechanism of toxicity. The method uses the derivatization of free thiol groups in GSH. Its performance was demonstrated for less explored tissues (lung, brain, and liver) in mouse. The combined extraction and analytical method has very low variability and good reproducibility, maximum coefficients of variance for within-run and between-run analyses under 8 %, and low limits of quantification; for GSH and GSSG, these were 0.2 nM (0.06 ng/mL) and 10 nM (6 ng/mL), respectively. The performance of the method was further demonstrated in a model experiment addressing changes in GSH and GSSG concentrations in lung of mice exposed to CdO nanoparticles during acute 72 h and chronic 13-week exposures. Inhalation exposure led to increased GSH concentrations in lung. GSSG levels were in general not affected; nonsignificant suppression occurred only after the longer 13-week period of exposure. The developed method for the sensitive detection of both GSH and GSSG in very low tissue mass enables these parameters to be studied in cases where only a little sample is available, i.e. in small organisms or in small amounts of tissue.

LC-ESI-MS/MS method for oxidative stress multimarker screening in the exhaled breath condensate of asbestosis/silicosis patients.

The sensitive assay method was developed for a parallel, rapid and precise determination of the most prominent oxidative stress biomarkers: 8-iso-prostaglandin F(2α) a lipid oxidation biomarker, o-tyrosine an amino acid oxidation biomarker and 8-hydroxy-2'-deoxy-guanosine a nucleic acid oxidation biomarker. The method consisted of a pre-treatment part, freeze drying (lyophilization), serving the purpose of biomarkers concentration from the exhaled breath condensate and detection method LC-ESI-MS/MS, where the selected reaction-monitoring mode was used for its extremely high degree of selectivity and the stable-isotope-dilution assay for its high precision of quantification. The developed method is characterized by the following parameters: the precision was higher than 84.3% and the mean accuracy (relative error) was determined lower than 11.6%. The method was tested on samples obtained from patients diagnosed with asbestosis and silicosis, occupational diseases induced by oxidative stress, and then compared with samples from healthy subjects. The difference in biomarkers' concentration levels found between the two groups was statistically significant.

Possibilities of early diagnosis of occupational asthma.

Occupational asthma is one of the most frequent occupational diseases of the respiratory tract in developed countries. Moreover, the diagnosis of occupational asthma is difficult because the confirmation of the occupational origin of the disease has an important impact on the career of the employee and many persons must involuntarily leave their work position. To avoid serious consequences, it is necessary to develop new methods which could disclose the incipient occupational asthma earlier than methods available nowadays or support the diagnosis in case of equivocal results (decrease in ventilatory parameters) of the bronchoprovocation tests. Exhaled breath condensate (EBC) analysis is a new non-invasive method which appears useful in occupational asthma diagnostics. Leukotrienes as obstruction markers and 8-isoprostane as an oxidative stress marker could be analysed from EBC. The concentrations of leukotrienes and 8-isoprostane were described to be elevated in EBC of asthmatic persons. Monitoring of leukotrienes and 8-isoprostane concentration changes in the EBC during the bronchoprovocation tests with allergens could bring new information about the pathophysiological changes in airways during inhalation tests with allergens. Induced sputum is a relatively non-invasive method which could be used in asthma diagnosis. The monitoring of the sputum cell count (especially changes of eosinophils) has a potential to be used for monitoring of asthma and during allergen challenge tests, too. The elevation of sputum eosinophils was described after allergen tests in several studies.

Exposure to silica and risk of ANCA-associated vasculitis.

BACKGROUND: Exposure to silica dust is considered to be one of etiological factors of antineutrophil cytoplasmic antibodies (ANCA) -associated vasculitis (AAV). METHODS: Subjects exposed to silica dust in Central Bohemia and followed in the Department of Occupational Medicine, Charles University, were selected for study. A group of 86 men exposed to SiO2 for at least 5 years were examined. The association between occupational exposure to silica dust and ANCA positivity is analyzed. RESULTS: The subjects had a mean age of 66.7 years, and mean exposure to silica of 22.3 years. ANCA were detected significantly more frequently in patients group (17.1%; P-ANCA 18x, C-ANCA 3x) than in controls (n = 28, mean age 64.2 years, P-ANCA 1x, i.e., 3.6%). ANCA positivity was found less frequently (7.1%) in the group with history of SiO2 exposure without signs of pronounced silicosis, than in the group with simple (30.3%) or complicated silicosis (36.0%). Odds ratio for ANCA positivity and relative risk estimate in patients with silicosis were highly significant. Among possible predictor factors for ANCA positivity, silicosis and tuberculosis were relevant. No typical AAV was present among the patients. CONCLUSION: Long-term silica exposure may be one of the exogenous factors contributing to ANCA production, however, silica exposure alone, without typical silicosis, was not associated with ANCA positivity.

Mercury intoxication from skin ointment containing mercuric ammonium chloride.

OBJECTIVE: A one-year follow-up was performed of a 21-year-old man with a 16-year history of diabetes mellitus type I, who had been using ointment containing 10% mercuric ammonium chloride (hydrargyrum amidochloratum; HgNH(2)Cl) for eczema for approximately 3 weeks. Tiredness, fasciculations on the extremities and poor control of diabetes appeared after the end of the ointment treatment. Nephrotic syndrome and hypertension were diagnosed 1 month later. Two months after the ointment application the patient was very weak with tremors of the hands, almost unable to walk, and had lost 20 kg of body weight. He had severe neurasthenic symptoms and his behaviour suggested acute psychosis. METHODS: Internal, neurological and neuropsychological examinations were performed. Mercury in urine was determined by flameless atomic absorption spectrometry. RESULTS: The urine mercury level on admission was 252.0 microg/l. He was treated with Dimaval, sodium (2,3)-dimercaptopropane(-1)-sulphonate capsules for 12 days (total dose 6.3 g). The highest urine mercury excretion during antidote treatment was 2336.0 microg/24 h. The patient had proteinuria of up to 11.10 g/24 h, and renal biopsy revealed diffuse membranous glomerulonephritis of the 1st stage without apparent diabetic nephropathy. Similarly, neuropathy did not have typical signs of diabetic neuropathy. His clinical condition started to improve during the first 2 weeks. Further follow-up has shown slow normalisation of renal functions. After 1 year, proteinuria decreased to 0.62 g/24 h and body weight normalised. Neuropsychological and electromyographic findings became almost normal. CONCLUSION: Severe intoxication developed after a short period of ointment application. Most signs of damage disappeared in the course of 1 year, except mild proteinuria and neuropathy. The evolution was favourable and confirmed the primary role of mercury intoxication in the severe deterioration of the clinical status of the patient.

Mobilization of mercury by DMPS in occupationally exposed workers and in model experiments on rats: evaluation of body burden.

The aim of the study was to evaluate the efficacy of DMPS (sodium-2,3-dimercapto-1-propane sulfonate) (Dimaval) administration for mobilizing mercury from the body in occupationally exposed people and experimental animals. Two doses of DMPS were administered at a 24-h interval to: (a) groups of people occupationally exposed to merkury--workers of the chloralkali industry (n = 43), and dentists (n = 12), (b) non-exposed individuals (n = 20), and (c) rats chronically exposed to mercury vapour at the concentration of 0.8 mg/m3 Hg degree (6 h/day, 5 days/week) for 15 weeks. In an out-patient mobilizing test, the urinary excretion of mercury 48 h after the administration of the first dose reached 1513 micrograms in the group of industrial workers, 132.6 micrograms in dentists, and 3.78 micrograms in controls. In rats, two consecutive doses of DMPS decreased kidney content of mercury by about 30% and 50% after oral and intraperitoneal administration, respectively. Kidney mercury burden was calculated on the basis of the data from animal and human studies of the mobilization of mercury via urine after DMPS treatment: 61, 2800 and 28,000 ng/g in controls, dentists and workers, respectively. It was estimated that two doses of DMPS mobilized 17-20% (after oral administration) and 25-30% (after intramuscular administration) of kidney mercury burden, both in the control and exposed subjects.

Occupational diseases in the Czech Republic in the year 1998. The need for unifying European standards/criteria for all occupational diseases.

In the Czech Republic, the Clinics and Departments for Occupational Medicine according to the legislation have the right to recognise occupational diseases. The diagnosis must correspond to the Czech list of occupational diseases, which is similar to the European list of occupational diseases. The exposure, sufficient enough to cause certain occupational disease, must be confirmed by regional industrial hygienists, responsible for hygienic control of the workplace. It is evident that the number of diseases is very much dependent upon the standards/criteria used to recognise occupational diseases. In the Czech Republic, the patients suffering from occupational diseases are given considerable financial compensations, which creates a great motivation for them to apply for occupational diseases. The article presents the overview of occupational diseases in the Czech Republic in the year 1998. The total number of diseases was 2111, the incidence per 100,000 employees was 45.8. It is necessary to present and discuss unifying criteria for occupational diseases in European countries, as well as the minimum level of the damage, that could be called an occupational disease. The criteria should be co-ordinated, because in a unified Europe, there will be many more possibilities for change in the workplace.