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Short term studies were performed to study biological effects of the common air pollutants SO or NO and their influence on the genotoxic activities of nitrosamines. Hepatocytes and lung cells were isolated from Sprague-Dawley rats which had inhaled 50 p.p.m. of SO or NO for 2 weeks. After incubating the cells for 1 h, genotoxicity was determined in hepatocytes by measuring DNA single-strand breaks induced by iV-nitroso-acetoxymethylmethylamine, -nitrosodimethylamine and -nitrosomethylbenzylamine. Parameters of toxicity (trypan blue exclusion and leakage of serum enzymes) were determined in both liver and lung cells also following 1 h incubation. The activities of aryl hydrocarbon hydroxylase (AHH), nitrosodimethylamine demethylase (NDMA-D) and glutathione-S-transferase (GST) were determined in subcellular microsomal fractions isolated from lung and liver tissues. Finally, as a measure of overall toxicity, the activities of various serum enzymes were determined in the blood serum of the rats. It was found that the induction of DNA single-strand breaks by three nitrosamines was decreased in hepatocytes from SO-treated animals. The viability of rat hepatocytes and of rat lung cells, as determined by trypan blue exclusion, was similar in all three treatment groups immediately after isolation, as well as after 1 h incubation with DMSO or with the nitrosamines. In contrast, the leakage of enzymes was different in hepatocytes of SO-treated rats, since lactate dehydrogenase activity was decreased. Leakage of enzymes from the lung cells did not differ from group to group, but was lower than from hepatocytes. Foreign compound metabolizing enzymes were mainly decreased in NO-treated animals, namely AHH, NDMA-D and GST in liver and GST in the lung. For SO-treated animals NDMAD was increased in liver and GST was decreased in lung. Blood serum enzyme levels were not greatly different from each other, except for lactate dehydrogenase which was elevated in SO-exposed animals. [ABSTRACT FROM PUBLISHER]

Although Alzheimer's dementia (AD) is not characterised any longer simply as the accumulation and deposition of amyloid beta (Aβ) peptides and hyperphosphorylation of tau proteins within the brain, excessive Aβ(42) deposition is still considered to play a major role in this illness. Aβ are able to adopt many differently aggregate forms, including amyloid fibrils as well as nonfibrillar structures (soluble Aβ(42) oligomers). It is not well-established that which Aβ(42) state is most responsible for AD or why. We wanted to verify which effects Aβ(42) oligomers and aggregated peptides have on gene expression, protein level and enzyme activity of insulin and amyloid precursor protein (APP) pathways in vitro. Human neuroblastoma cells (SH-SY5Y) were treated with varying concentrations of soluble and aggregated Aβ(42). Treatment effects on β-secretase (BACE), glycogen synthase kinase 3α (GSK3α), glycogen synthase kinase 3β (GSK3β), phosphatidylinositol-3 kinase (PI-3K), insulin-degrading enzyme (IDE), insulin-receptor substrate 1 (IRS1), insulin receptor (INSR) and monoamine oxidase B (MAO-B) were investigated via quantitative-PCR, western blot, ELISA and enzyme activity assay. We could find different effects of soluble and aggregated peptides especially on gene/protein expression of GSK3β and INSR and on GSK3β and MAO-B activity. Soluble peptides showed significant effects leading to increased gene expression and protein amount of GSK3β and to decreased level of gene and protein expression of INSR. MAO-B activity was enhanced after treatment with aggregated peptides and strongly inhibited after soluble Aβ(42) treatment. Our data might provide insights into selective effects of specific forms of Aβ(42) aggregates in AD.

Giardia duodenalis causes enteric infections in humans and animals worldwide. Inefficiency of metronidazole is commonly reported in the veterinary clinic routine in the treatment of giardiasis in dogs and cats. The aim of this study was to evaluate the efficacy of secnidazole in the control of infection caused by G. duodenalis in naturally infected cats. For this purpose two experiments were carried out. In the first experiment seven cats were infected with G. duodenalis and treated orally with a single dose of secnidazole (30 mg kg(-1)). In the second experiment a total of 16 cats were used, 11 naturally infected with G. duodenalis and five negative for the parasite. Animals were divided into three groups: group A (n=5) was composed by non-infected animals (negative control), group B (n=5) consisted of infected but untreated animals and group C (n=6) was composed by cats treated orally with a single dose of secnidazole (30 mg kg(-1)). Hematological and biochemical parameters were evaluated before and after treatment. The first experiment reached 100% of efficacy because no cysts were found in the feces after treatment. However, doubts about intoxication and interference with hematological and biochemical parameters came to light. No side effects were observed, and the biochemical and hematological parameters of treated animals remained within physiological range, except for one feline which had elevation of liver enzymes. Based on these results, the utilization of secnidazole could be suggested for the treatment of giardiasis in cats. The main advantage of this treatment is that only a single dose is required, which is interesting in animals hard to handle like cats., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Toxicological mechanisms involved in organotropism of tumor induction may include cell-specific metabolic activation of the carcinogen, in vivo distribution of active metabolites and persistance of induced DNA damage. In order to elucidate which factors are involved in the organotropic action of environmentally relevant N-nitrosamines, we have studied their genotoxic and cytotoxic effects within primary intact cells of lung and kidney. The end-points determined were cytotoxicity by trypan blue exclusion and DNA single-strand break (SSB) induction by alkaline filter elution. The assays were performed in vitro to determine organ-specific metabolic activation by incubating the cells with the test compounds. The results obtained with N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosodiethanolamine (NDEIA), N-nitrosoethylvinylamine (NEVA), N-nitrosodibutylamine (NDBA), N-nitrosobutylbutanolamine (NBBOH), N-nitrosobutylcarboxypropylamine (BCPN), N-nitrosomethylbenzylamine (NMBzA) and N-nitrosodibenzylamine (NDBzA) indicate that several compounds may be activated to reactive metabolites by cells of kidney and lung, NDBzA revealing the highest degree of cytotoxicity. In contrast, genotoxicity in kidney cells was induced only by NBBOH and BCPN and at relative low levels. Primary lung cells could not be employed as indicators for genotoxic effects in vitro because the cell yield was not sufficient to perform the alkaline elution assay. To assess the distribution of NDMA in the whole rat and the persistence of the induced DNA damage in the two organs, further studies were carried out after oral application of 1, 2, 4, 10, 20, 32 and 40 mg/kg to the animals. Following 1 h exposure of rats to NDMA, the lowest effective genotoxic dose for lung and kidney was 2 mg NDMA/kg body wt. A plateau was achieved after a dose of 20 mg/kg in both organs. Furthermore, the persistence of DNA damage was studied in the lung. After 4 h exposure, DNA damage was still detectable at 32 mg NDMA/kg, but for the lower doses it was reduced nearly to control levels. After 16 h exposure the SSB rate in lung cells was reduced for all dose levels except for the highest dose of 40 mg/kg.

1. The in vitro studies showed that organ specific metabolic activation does not appear to play a predominant role for the in vivo activities of the studied nitrosamines 2. The in vivo studies following 1 h exposure of rats with the nitrosamines can differentiate between organs susceptible for genotoxicity and and those which are not. Nontarget organs in carcinogenicity can not be identified exclusively. 3. The additional study of persistence of genotoxicity may identify organs susceptible for carcinogenicity. Presently, we are working on new techniques to detect DNA SSB and other events with microscale methods. This is necessary to allow a more complete elucidation of genotoxicity in remote target organs and with other carcinogens which may not induce DNA SSB. Accordingly in the near future we expect to have even more versatile tools available to study toxicokinetics of foreign compound. Meanwhile our work with N-nitrosamines is continuing in order to better understand their in vivo modes of action and to better evaluate their burden and risk for man.