[Reducing the exposure of patients and healthcare teams to cytotoxins]. / Réduire l'exposition des patients et des équipes soignantes aux cytotoxiques.

In order to prevent human and environmental risks related to the handling of cytotoxins and cytostatics, health care institutions are implementing precautionary measures. Information and training actions for health professionals, nurses, orderlies and pharmacy assistants are also part of the system. Example with a team in Lyon.

Evaluation of biological effects of nanomaterials. Part I. Cyto- and genotoxicity of nanosilver composites applied in textile technologies.

OBJECTIVES: The aim of this study was to investigate the cyto- and genotoxicity of nanocomposites (NCs) and generation of reactive oxygen species (ROS) as a result of particle-cell interactions. MATERIALS AND METHODS: Titanium dioxide (TiO(2)-Ag) and ion-exchange resin (Res-Ag), both coated with silver (Ag), were examined. The murine macrophage J774A.1 cells were incubated in vitro with NC at different concentrations for 24 h. Cytotoxicity was analyzed by the methylthiazolyldiphenyl-tetrazolium bromide reduction test (MTT reduction test). ROS generation was assessed by incubation of cells with dichlorodihydrofluorescein diacetate (DCF) and flow cytometry. DNA damage was detected by comet assay and included single-strand breaks (SSB), alkali-labile sites (ALS) and oxidative DNA damage after formamidopyrimidine glycosylase (FPG) treatment. The tail moment was used as an indicator of DNA damage. RESULTS: TiO(2)-Ag was not cytotoxic up to 200 µg/ml, whereas IC(50) for Res-Ag was found to be 23 µg/ml. Intracellular ROS levels were elevated after 4 h of exposure to Res-Ag at the concentration of 50 µg/ml. Both types of NC induced fragmentation of DNA strands, but only one of the composites caused damage to purine bases. TiO(2)-Ag induced SSB of DNA at concentrations of 10 and 5 µg/ml. For Res-Ag, a concentration-dependent increase in tail moments was observed. CONCLUSIONS: Silver-coated nanocomposites (both TiO(2)-Ag and Res-Ag) may cause genotoxic effects in murine macrophages J774A.1. Res-Ag increased generation of ROS which suggested that toxicity of Res-Ag in murine macrophages is likely to be mediated through oxidative stress. This paper will support industry and regulators alike in the assessment of hazards and risks and methods for their mitigation at the earliest possible stage in material and product development.

Further evidence on mitochondrial targeting of ß-amyloid and specificity of ß-amyloid-induced mitotoxicity in neurons.

BACKGROUND/AIMS: Impaired mitochondrial function has been described in Alzheimer's disease. We previously reported that, in neuronal cells, ß-amyloid 1-42 (Aß(1-42)) is targeted to mitochondria. We have also reported that, when incubated with isolated rat brain mitochondria, Aß(1-42) inhibits complex IV, uncouples the mitochondrial respiratory chain, and promotes opening of the membrane permeability transition pore. Here, we further analyzed the targeting and mitotoxicity of Aß(1-42). METHODS AND RESULTS: Immunoelectron microscopy revealed that the mitochondrial targeting of Aß(1-42) was concentration- and time-dependent. Incubation of human neuroblastoma cells with Aß(1-42) increased the release of adenylate kinase, a mitochondrial enzyme released after membrane permeability transition pore opening. However, it failed to trigger DNA fragmentation and apoptosis, suggesting that the ability of this peptide to uncouple the respiratory chain underlies its mitotoxicity and cytotoxicity. Aß(1-42) targeting to mitochondria was blocked by caprospinol, a steroid derivative shown to protect neuronal cells against Aß(1-42)-induced neurotoxicity. Further experiments revealed that the mitotoxic effect of Aß(1-42) is specific to its primary amino acid sequence and suggested that it may be also related to its tertiary structure. Importantly, the mitotoxic effect of Aß(1-42) was not restricted to brain cells, indicating that it is not cell- or tissue-specific. CONCLUSION: Taken together, these results suggest that extracellular Aß(1-42) targets neuronal mitochondria to exert its toxic effects.

Signal transduction pathways and cellular intoxication with Clostridium difficile toxins.

In cultured cells the cytopathic effects (CPE) of Clostridium difficile toxins A and B are superficially similar. The irreversible CPEs involve a reorganization of the cytoskeleton, but the molecular details of the mechanism(s) of action are unknown. As part of the work to elucidate the events leading to the CPE, cultured cells were preincubated with agents known to either stimulate or inhibit some major signal transduction pathways, whereupon toxin was added and the development of the CPE was followed. Both toxin-induced CPEs were enhanced by phorbol esters and mezerein, which stimulate protein kinase C, while they were inhibited by the phospholipase A2 inhibitors quinacrine and 4-bromophenacylbromide. Agents affecting certain G-proteins, cGMP and cAMP levels, phosphatases, prostacyclin, lipoxygenase, and phospholipase C did not affect the development of the CPE of either toxin. Thus, the cytoskeletal effect induced by toxins A or B appears to require PLA2 activity and involves at least part of a protein kinase C-dependent pathway, but not pertussis toxin-sensitive G-proteins, cyclic nucleotides, eicosanoid metabolites, or phospholipase C activity. In addition, both toxins were shown to activate phospholipase A2.

Diarrhea and colitis associated with antimicrobial therapy in man and animals.

Antimicrobial agent-induced ileocecitis of laboratory animals and colitis of man share common features. The significance of a newly described toxin in these two entities, the apparent source of the toxin (Clostridium difficile) and characteristics of the toxin are reviewed. Methods of toxin detection, isolation and rapid identification of C. difficile, and possible modes of therapy for antimicrobial agent-associated colitis of man are discussed.