Breast cancer is the most frequent cancer in women. It is believed that among the causes of breast cancer, hereditary factors account for only 5-10% of risk and the environmental exposures to environmental contaminants account for an additional 30-50% of risk. This paper summarizes findings related to the risk of breast cancer due to exposure to following environmental contaminants: polycyclic aromatic hydrocarbons, polychlorinated biphenyls and dioxins, organochlorine pesticides, organophosphorous pesticides, bisphenol A, phthalates, parabens, organic solvents, atmospheric pollutants, alkylphenols, metals, ionizing radiation, electromagnetic field and light pollution. Results obtained in in vitro experiments with breast cancer cell lines and in vivo with model rodents as well as in population based case-control studies are presented and the mode of action of individual environmental contaminants on mammary gland is discussed. Attention is also devoted to the effects of the timing of exposure to environmental contaminants (mainly exposition during development of the mammary gland) on breast cancer risk. Outcomes of professional exposure to some environmental contaminants on breast cancer risk are analysed as well
Metabolomics - Useful Tool for Study of Plant Responses to Abiotic Stresses
Abiotic stresses are produced by inappropriate levels of physical components of the environment and cause plant injury through unique mechanisms that result in specific responses. Metabolomics is a relatively new approach aimed at improved understanding of metabolic networks and the subsequent biochemical composition of plants and other biological organisms. The paper is focused on the use of metabolomics, metabolic profiling and metabolic fingerprinting to study plant responses to some environmental stresses (eg elevated temperature, chilling and freezing, drought, high salinity, UV radiation, high ozone levels, nutrient deficiency, oxidative stress, herbicides and heavy metals). Attention is also devoted to the effects of some environmental factors on plants such as high or low levels of CO2 or different levels of irradiance. Alterations of plants metabolites due to multiple abiotic stresses (drought-heat, drought-salinity, elevated CO2-salinity) are analysed as well. In addition, metabolomic approach to study plant responses to some artificial abiotic stresses, mechanical stress or pulsed electric field-induced stress is discussed. The most important analytical methods applied in metabolomics are presented and perspectives of metabolomics exploitation in the future are outlined, too.
Metal nanoparticles (MNPs) belong mostly to the engineered type of nanoparticles and have not only unique physical and chemical properties but also different biological actions. In recent years, noble MNPs and their nano-sized agglomerates (collectively referred to as nanoparticles or particles in the subsequent sections) have been the subjects of much focused research due to their unique electronic, optical, mechanical, magnetic and chemical properties that can be significantly different from those of bulk materials. To enhance their use, it is important to understand the generation, transport, deposition, and interaction of such particles. Synthesis of MNPs is based on chemical or physical synthetic procedures and by use of biological material (“green synthesis” as an environmentally benign process) including bacteria, algae and vascular plants (mainly metallophytes). In biological methods for preparation of metal nanoparticles mainly leaf reductants occurring in leaf extracts are used. MNPs can be formed also directly in living plants by reduction of the metal ions absorbed as a soluble salt, indicating that plants are a suitable vehicle for production of MNPs. These methods used for preparation of MNPs are aimed to control their size and shape. Moreover, physicochemical properties of MNPs determine their interaction with living organisms. In general, inside the cells nanoparticles might directly provoke either alterations of membranes and other cell structures or activity of protective mechanisms. Indirect effects of MNPs depend on their physical and chemical properties and may include physical restraints, solubilization of toxic nanoparticle compounds or production of reactive oxygen species. Toxic impacts of MNPs on plants is connected with chemical toxicity based on their chemical composition (eg release of toxic metal ions) and with stress or stimuli caused by the surface, size and shape of these nanoparticles. Positive effects of MNPs were observed on the following plant features: seed germination, growth of plant seedlings, stimulation of oxygen evolution rate in chloroplasts, protection of chloroplasts from aging for long-time illumination, increase of the electron transfer and photophosphorylation, biomass accumulation, activity of Rubisco, increase of quantum yield of photosystem II, root elongation, increase of chlorophyll as well as nucleic acid level and increase in the shoot/root ratio. However, it should be stressed that MNPs impact on human and environmental health remains still unclear.
The effects of five organomercury compounds (methylmercuric chloride, phenylmercuric acetate, phenylmercuric borate, phenylmercuric citrate and diphenylmercury) on photosynthetic electron transport (PET) in spinach chloroplasts were investigated. The IC50 values of organomercury compounds related to PET inhibition in spinach chloroplasts varied in the range from 468 mmol dm-3 to 942 mmol dm-3 and were approximately by one order higher than the corresponding value determined for HgCl2 applied also in DMSO solution (IC50 = 58 mmol dm-3). Due to extremely low aqueous solubility of diphenylmercury, the corresponding IC50 value could not be determined. Using EPR spectroscopy as probable sites of action of organomercury compounds in photosynthetic apparatus ferredoxin on the acceptor side of PS 1 and the quinone electron acceptors QA or QB on the reducing side of PS 2 were suggested.
Adverse effect of nickel on hydroponically cultivated plants of two Brasssica napus L. cultivars (Verona and Viking) was investigated. Dry mass of shoots and roots as well as some biochemical characteristics (concentration of photosynthetic pigments, TBARS and proteins) of plant leaves were determined. In addition, the content of nickel in plant organs was estimated. Visible symptoms of Ni toxicity were notable already at the lowest applied concentration (6 μmol · dm-3). Higher applied Ni concentrations (24, 60 and 120 μmol · dm-3) resulted in moderate to strong toxic effects on plants of both studied cultivars. After application of 6 and 12 μmol · dm-3 Ni shoot dry mass of cv. Viking was substantial lower than that of cv. Verona. Decrease of root dry mass after treatment with 6, 12 and 120 μmol · dm-3 Ni was similar for both cultivars. Strong decrease in content of photosynthetic pigments was observed after application of 120 μmol · dm-3. Comparing to the control, the content of these pigments in leaves of plants dropped under 50% (both cultivars). The highest applied Ni concentration 120 μmol · dm-3 caused that protein content in leaves dropped by 39% (cv. Verona) and 37% (cv. Viking) comparing to the control plants. After application of 120 μmol · dm-3 Ni the content of malondialdehyde in leaves was 2.64- (Viking) and 2.31- (Verona) times higher than that of control. Nickel amounts accumulated in roots of plants were higher than those in shoots. Accumulated Ni amounts in roots of cv. Verona plants were 1.3- (120 μmol · dm-3) to 1.9- (6 μmol · dm-3) times lower than those of cv. Viking plants, whereas metal amounts accumulated in shoots of cv. Verona plants were 1.2- (120 μmol · dm-3) to 1.8- (6 μmol · dm-3) times lower than those of cv. Viking plants.
Nanoagrochemicals, such as nanopesticides, nanofertilizers or plant growth stimulating nanosystems, were primarily designed to increase solubility, enhance bioavailability, targeted delivery, controlled release and/or protection against degradation resulting in the reduced amount of applied active ingredients and finally in a decrease of dose-dependent toxicity/burden. This paper is a comprehensive up-to-date review related to the preparation and the biological activity of nanoformulations enabling gradual release of active ingredient into weeds and the body of pests and controlled release of nutrients to plants. The attention is also devoted to the decrease of direct environmental burden and economic benefits due to application of nanoformulations, where less amount of active ingredient is needed to achieve the same biological effect in comparison with bulk. The application of nanotechnology in the areas such as food packaging, food security, encapsulation of nutrients and development of new functional products is analysed. The use of nanoparticles in biosensors for detection of pathogens and contaminants as well as in DNA and gene delivery is discussed as well. Benefits and health risks of nanoagrochemicals are highlighted, and special attention is given to nanoecotoxicology and guidelines and regulatory documents related to the use of nanoformulations in agriculture and food industry.
The effects of dithiaden on nitric oxide production by RAW 264.7 cells
Asreported in our previous studies, dithiaden (an antagonist of histamine H1-receptor, used clinically as an anti-allergic or anti-emetic drug) in a concentration range of 5×10-5-10-4 M decreased the production of reactive oxygen species by phagocytes. In this study we investigated the influence of dithiaden on nitric oxide (NO) production by LPS-stimulated macrophages.
The cell viability in the presence of 10-4-5×10-5 M dithiaden was evaluated by an ATP-test. RAW 264.7 cells (2.5×106/well) were preincubated with dithiaden for 60 mins and subsequently stimulated with 0.1 μg/ml of bacterial lipopolysaccharide. After incubating for 24 hours the NO production was determined spectrophotometrically using Griess reaction as a concentration of nitrites (the end product of NO metabolism) accumulated in the cell supernatants. The expression of inducible nitric oxide synthase (iNOS) in cell-lysates was evaluated using Western blot analysis. Scavenging properties of dithiaden against NO were evaluated amperometrically. Our data demonstrate that dithiaden in the concentration of 5×10-5 M (approved by ATP test as non toxic) caused a significant decrease in the accumulation of nitrites, and in addition, this decline was followed by a marked reduction of iNOS protein expression. Amperometrical analysis did not show any scavenging properties of dithiaden against NO.
From this data it can be suggested that the inhibition effect of dithiaden on macrophage NO production is caused exclusively by the suppression of iNOS protein expression.