Bladder cancer, a review of the environmental risk factors

<p>Abstract</p> <p>Background</p> <p>Many epidemiological studies and reviews have been performed to identify the causes of bladder cancer. The aim of this review is to investigate the links between various environmental risk factors and cancer of the bladder.</p> <p>Methods</p> <p>A systematic literature search was performed using PubMed, Science Direct, Scopus, Scholar Google and Russian Google databases to identify reviews and epidemiological studies on bladder cancer risk factors associated with the environment published between 1998 and 2010. Only literature discussing human studies was considered.</p> <p>Results</p> <p>Smoking, mainly cigarette smoking, is a well known risk factor for various diseases, including bladder cancer. Another factor strongly associated with bladder cancer is exposure to arsenic in drinking water at concentrations higher than 300 µg/l. The most notable risk factor for development of bladder cancer is occupational exposure to aromatic amines (2-naphthylamine, 4-aminobiphenyl and benzidine) and 4,4'-methylenebis(2-chloroaniline), which can be found in the products of the chemical, dye and rubber industries as well as in hair dyes, paints, fungicides, cigarette smoke, plastics, metals and motor vehicle exhaust. There are also data suggesting an effect from of other types of smoking besides cigarettes (cigar, pipe, Egyptian waterpipe, smokeless tobacco and environmental tobacco smoking), and other sources of arsenic exposure such as air, food, occupational hazards, and tobacco. Other studies show that hairdressers and barbers with occupational exposure to hair dyes experience enhanced risk of bladder cancer. For example, a study related to personal use of hair dyes demonstrates an elevated bladder cancer risk for people who used permanent hair dyes at least once a month, for one year or longer.</p> <p>Conclusion</p> <p>Smoking, in particular from cigarettes, exposure to arsenic in drinking water, and occupational exposure to aromatic amines and 4,4'-methylenebis(2-chloroaniline) are well known risk factors for various diseases including bladder cancer. Although the number of chemicals related to occupational exposure is still growing, it is worth noting that it may take several years or decades between exposure and the subsequent cancer.</p

Functionalized porous silica&maghemite core-shell nanoparticles for applications in medicine: design, synthesis, and immunotoxicity

Aim To determine cytotoxicity and effect of silica-coated magnetic nanoparticles (MNPs) on immune response, in particular lymphocyte proliferative activity, phagocytic activity, and leukocyte respiratory burst and in vitro production of interleukin-6 (IL-6) and 8 (IL-8), interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), and granulocyte macrophage colony stimulating factor (GM-CSF). Methods Maghemite was prepared by coprecipitation of iron salts with ammonia, oxidation with NaOCl and modified by tetramethyl orthosilicate and aminosilanes. Particles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier-transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). Cytotoxicity and lymphocyte proliferative activity were assessed using [3H]-thymidine incorporation into DNA of proliferating human peripheral blood cells. Phagocytic activity and leukocyte respiratory burst were measured by flow cytometry; cytokine levels in cell supernatants were determined by ELISA. Results γ-Fe2O3&SiO2-NH2 MNPs were 13 nm in size. According to TEM, they were localized in the cell cytoplasm and extracellular space. Neither cytotoxic effect nor significant differences in T-lymphocyte and T-dependent Bcell proliferative response were found at particle concentrations 0.12-75 μg/cm2 after 24, 48, and 72 h incubation. Significantly increased production of IL-6 and 8, and GMCSF cytokines was observed in the cells treated with 3, 15, and 75 μg of particles/cm2 for 48 h and stimulated with pokeweed mitogen (PHA). No significant changes in TNF-α and IFN-γ production were observed. MNPs did not affect phagocytic activity of monocytes and granulocytes when added to cells for 24 and 48 h. Phagocytic respiratory burst was significantly enhanced in the cultures exposed to 75 μg MNPs/cm2 for 48 h. Conclusions The cytotoxicity and in vitro immunotoxicity were found to be minimal in the newly developed porous core-shell γ-Fe2O3&SiO2-NH2 magnetic nanoparticles

Detection of alkylation damage in human lymphocyte DNA with the comet assay.

The enzyme 3-methyladenine DNA glycosylase II (AlkA) is a bacterial repair enzyme that acts preferentially at 3-methyladenine residues in DNA, releasing the damaged base. The resulting baseless sugars are alkali-labile, and under the conditions of the alkaline comet assay (single cell gel electrophoresis) they appear as DNA strand breaks. AlkA is not lesion-specific, but has a low activity even with undamaged bases. We have tested the enzyme at different concentrations to find conditions that maximise detection of alkylated bases with minimal attack on normal, undamaged DNA. AlkA detects damage in the DNA of cells treated with low concentrations of methyl methanesulphonate. We also find low background levels of alkylated bases in normal human lymphocytes.Single cell gel electrophoresis (the comet assay) is widely used for the detection of strand breaks in nuclear DNA. It is particularly appropriate for studying the low background levels of damage present in normal human cells, such as peripheral lymphocytes. The cells are embedded in agarose on a microscope slide and lysed with Triton X-100 and 2.5 M NaCl, which remove cytoplasm and most nuclear proteins, but leave the DNA, in supercoiled form, as nucleoids. After incubation in alkali, the DNA is electrophoresed at high pH; DNA is drawn out to form a 'tail' (hence the name 'comet assay') - but only if breaks are present to relax the supercoiling of the nucleoid DNA. In order to increase its sensitivity and selectivity, we have incorporated into the assay an extra step in which the nucleoid DNA is digested with a lesion-specific endonuclease; the additional breaks revealed with this procedure indicate the presence of the particular lesion. So far, endonuclease III (NTH, specific for oxidised pyrimidines) (Collins et al., 1993), formamidopyrimidine DNA glycosylase (FPG, acting on ring-opened purines and the major purine oxidation produce, 8-oxoguanine) (Dušinská & Collins, 1996) and T4 endonuclease V (recognising UV-induced cyclobutane pyrimidine dimers) (Collins et al., 1997b) have been successfully employed. Amongst other things, we have estimated background levels of DNA oxidation (Collins et al., 1997a), and have found this damage to be elevated in human diseases such as diabetes and ankylosing spondylitis (Dušinská et al., 1999).We now report the use of AlkA, a bacterial repair enzyme whose main substrate is 3-methyladenine in DNA, though it also recognises - with lower efficiency - other modified bases (Lindahl, 1993). A recent report (Berdal et al., 1998) suggests that repair enzymes supposedly specific for alkylated bases may in fact create breaks non-selectively (though much less efficiently) at normal bases. Given the size of the genome, even a low efficiency of non-specific breakage could significantly interfere in estimations of background levels of alkylation damage. We reasoned that, by employing a range of concentrations of the enzyme, and carrying out incubations for different lengths of time, we might find a concentration at which only the alkylated bases would be detected, so that the number of breaks would increase to a certain level and then plateau. After optimising reaction conditions, we tested the assay on lymphocytes from different individuals, and also, as a positive control, examined alkylation damage induced by methyl methanesulphonate

Automotive airborne brake wear debris nanoparticles and cytokinesis-block micronucleus assay in peripheral blood lymphocytes: a pilot study

Motor vehicle exhaust and non-exhaust processes play a significant role in environmental pollution, as they are a source of the finest particulate matter. Emissions from non-exhaust processes include wear-products of brakes, tires, automotive hardware, road surface, and traffic signs, but still are paid little attention to. Automotive friction composites for brake pads are composite materials which may consist of potentially hazardous materials and there is a lack of information regarding the potential influence of the brake wear debris (BWD) on the environment, especially on human health. Thus, we focused our study on the genotoxicity of the airborne fraction of BWD using a brake pad model representing an average low-metallic formulation available in the EU market. BWD was generated in the laboratory by a full-scale brake dynamometer and characterized by Raman microspectroscopy, scanning electron microscopy, and transmission electron microscopy showing that it contains nano-sized crystalline metal-based particles. Genotoxicity tested in human lymphocytes in different testing conditions showed an increase in frequencies of micronucleated binucleated cells (MNBNCs) exposed for 48 h to BWD nanoparticles (NPs) (with 10% of foetal calf serum in culture medium) compared with lymphocytes exposed to medium alone, statistically significant only at the concentration 3 µg/cm2 (p=0.032).Web of Science14844944

Toxicity of the airborne brake wear debris

Particulate air pollution from road traffic currently represents significant environmental and health issue. Attention is also paid to the "non-exhaust pollution sources," which includes brake wear debris. During each brake application, the airborne and nonairborne particles are emitted into the environment due to wear. High temperatures and pressures on the friction surfaces initiate chemical and morphological changes of the initial components of brake pads and rotating counterparts. Understanding of impact of matter released from brakes on health is vital. Numerous studies clearly demonstrated that particulate matter caused potential adverse effects related to cytotoxicity, oxidative stress, stimulation of proinflammatory factors, and mutagenicity on the cellular level. This paper compiles our main results in the field of genotoxicity, immunotoxicity, and aquatic toxicity of airborne brake wear particles. The brake wear particles were generated using an automotive brake dynamometer. In vitro human peripheral blood cell model was used for the genotoxicity and immunotoxicity. Assessment of aquatic toxicity was performed on the green algae Raphidocelis subcapitata. Obtained results point to potency of toxicity related to the generated airborne brake wear debris.Web of Science101251

Comprehensive assessment of nephrotoxicity of intravenously administered sodium-oleate-coated ultra-small superparamagnetic iron oxide (USPIO) and titanium dioxide (TiO2) nanoparticles in rats

As a main excretory organ, kidney is predisposed to direct/indirect injury. We addressed the potential nephrotoxic effects following expositions of healthy rats to nanoparticle (NP) loads relevant to humans in a situation of 100% bioavailability. Up to 4 weeks after administration, a single iv bolus of oleate-coated ultra-small superparamagnetic iron oxide NPs (in dose of 0.1%, 1.0% and 10.0% of LD50) or TiO2 NPs (1.0% of LD50) did not elicit decline in renal function, damage to proximal tubules, alterations in: renal histology or expression of pro-inflammatory/ pro-fibrotic genes, markers of systemic or local renal micro-inflammation or oxidative damage. Antioxidant enzyme activities in renal cortex, mildly elevated at 24 h, completely restored at later time points. Data obtained by multifaceted approach enable the prediction of human nephrotoxicity during preclinical studies, and may serve as comparison for alternative testing strategies using in vitro and in silico methods essential for the NP-nephrotoxicity risk assessment