Michaela Zeiner

Toxic and biochemical effects of zinc in Caco-2 cells

Zinc (in relatively high concentrations) can be toxic to intestinal cells. The aim of the present study was to quanitfy cellular injury in preconfluent, colonic cancerous cells and in postconfluent, differentiating human intestinal Caco-2 cells. Cellular damage was measured by using cell proliferation, lactate dehydrogenase (LDH)-release, and apoptosis studies. Furthermore, the activities of the major antioxidative enzymes [superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase] and differentiation markers (alkaline phosphatase and aminopeptidase-N) were determined after exposure of the cells to increasing amounts of zinc sulfate. Proliferation and viability decreased in a concentration-dependent manner. A noticeable increase of LDH-release correlated to cell rounding and detachment at relatively high zinc levels (200 muM) was observed in both groups of cells. Above 100 muM of zinc, significant apoptotic activity was found in the preconfluent cells. Zinc supplementation did not alter SOD activities. However, GPx and, in part, catalase activities tended to be higher in zinc-treated cells (nevertheless the results were not significant). Differentiation markers were noticeably induced by increasing amounts of zinc, especially in the preconfluent cells. In conclusion, we suggest that the susceptibility to zinc induced damage is equal in both confluentation groups of Caco-2 cells. Risk assessment for high concentrations seems recommendable.

ICP-AES determination of minor- and major elements in apples after microwave assisted digestion

The aim of this paper was to determine the content of minor and major elements in apples by inductively coupled plasma atomic emission spectrometry (ICP-AES). Prior to ICP-AES measurement, dried apples were digested in a microwave assisted digestion system. The differences in the measured element concentrations after application of open and closed microwave system as sample preparation procedures are discussed. In whole apples, flesh and peel Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sr and Zn were analysed after optimisation and validating the analytical method using ICP-AES. The accuracy of the method determined by spiking experiments was very good (recoveries 88-115%) and the limits of detection of elements of interest were from 0.01 up to 14.7 μg g(-1). The reference ranges determined in all apple samples are 39-47 mg g(-1) for K, 9-14 mg g(-1) for Na, 3-7 mg g(-1) for Mg, 3-7 μg g(-1) for Zn, 0.7-2.8 μg g(-1) for Sr. The range of Mn in peel 4-6 μg g(-1) is higher compared to whole apple from 0.7 to 1.7 μg g(-1). Cd is found only in peel, in the concentration range of 0.4-1.1 μg g(-1).

Determination of 28 selected elements in textiles by axially viewed inductively coupled plasma optical emission spectrometry

A simple, robust and reliable analytical procedure for the determination of 28 selected elements, namely Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Hg, Mg, Mn, Mo, Na, Ni, Pb, Sc, Si, Se, Sn, Sm, Sr, Tl, V, and Zn in textile materials by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave digestion of samples was optimized and validated in this work. The total amount of elements present in textile samples was determined after microwave digestion of materials in 7 mol/L nitric acid within the optimal working program: 5 min at 150°C (power 250 W), 15 min 180°C (300 W) and 20 min at the maximum temperature of 200°C (350 W). For the quality control reasons, which were ascertained by analysis of the certified cotton trace elements reference material IAEA-V9, the ICP-OES method was optimized through several parameters: by comparing Meinhard and Gemcone Low Flow nebulizers efficiency, ranging nebulizer gas flows from 0.6 to 1.0 L/min, ranging sample flows from 0.8 to 1.2 mL/min, testing RF power from 1200 to 1400 W, detecting data acquisition time (read time) from 0 to 527 s, ranging washing (delay) time from 0 to 408 s, as well as by checking the occurring interferences for the optimal line selection. Validation included determination of linearity, selectivity, accuracy, reproducibility, precision and limits of detection calculated for all 28 selected elements of interest. The developed analytical procedure was successfully applied on textile fibers (cotton, flax and hemp) as well as on standard knitted textile sample materials (cotton and wool).

Removal of Cr, Mn, and Co from textile wastewater by horizontal rotating tubular bioreactor.

Environmental pollution by industrial wastewaters polluted with toxic heavy metals is of great concern. Various guidelines regulate the quality of water released from industrial plants and of surface waters. In wastewater treatment, bioreactors with microbial biofilms are widely used. A horizontal rotating tubular bioreactor (HRTB) is a combination of a thin layer and a biodisc reactor with an interior divided by O-ring shaped partition walls as carriers for microbial biomass. Using a biofilm of heavy metal resistant bacteria in combination with this special design provides various advantages for wastewater treatment proven in a pilot study. In the presented study, the applicability of HRTB for removing metals commonly present in textile wastewaters (chromium, manganese, cobalt) was investigated. Artificial wastewaters with a load of 125 mg/L of each metal underwent the bioreactor treatment. Different process parameters (inflow rate, rotation speed) were applied for optimizing the removal efficiency. Samples were drawn along the bioreactor length for monitoring the metal contents on site by UV-vis spectrometry. The metal uptake of the biomass was determined by ICP-MS after acidic microwave assisted digestion. The maximum removal rates obtained for chromium, manganese, and cobalt were: 100%, 94%, and 69%, respectively.

Pharmacological levels of copper exert toxic effects in Caco-2 cells.

Copper might be toxic to human intestinal cells because of its ability to catalyze the formation of free radicals. The aim of the present study was to quantify toxicological effects of increasing copper concentrations in preconfluent, colonic cancerous cells as well as in postconfluent, differentiating Caco-2 cells. Our results indicate that postconfluent cells might be more sensitive to copper toxicity. A significant rise of lactate dehydrogenase (LDH) release (150 µM or above) and decrease of cell proliferation (100 µM or above) with increasing copper levels was found, as compared to the control. To the contrary, preconfluent cells were not significantly affected by copper (LDH release) or, if so, only at a concentration of 250 µM (proliferation). Loss of viability and morphological changes, including loss of adherence and cell rounding, were visible after incubation with 250 µM copper in both groups. Superoxide dismutase (SOD) activities were not affected by copper. Glutathione peroxidase (GSH-Px) and catalase activities were higher in copper-treated cells, especially in the postconfluent ones (nevertheless, the results were not significant because of high standard deviations). In conclusion, we demonstrated that copper exerts intracellular, toxicological effects on both groups of Caco-2 cells, although the effects seem to be more evident in the postconfluent (enterocytelike) group. Risk assessment, especially for high concentrations, might be of special interest.

Reference concentrations of trace elements in urine of the budapestian population

Reference values in biological specimens are crucial to estimate the type and magnitude of environmental and occupational exposure: Because of its importance in the excretion of noxious substances and to the noninvasive mode of its collection, urine is a useful specimen for monitoring studies. Thus, the concentrations of six trace elements (Al, Co, Mo, Nb, Ni, and Ti) were determined in 100 urine samples of the Budapestian population by inductively coupled plasma-mass spectrometry. The obtained creatinine adjusted concentrations (medians) are (in μg/g) 9.9, 0.6, 53.5, 0.4, 1.5, and 8.5 for Al, Co, Mo, Nb, Ni, and Ti, respectively.

Influence of soil composition on the major, minor and trace metal content of Velebit biomedical plants.

The use of medical herbs for the treatment of many human diseases is increasing nowadays due to their mild features and low side effects. Not only for their healing properties, but also for their nutritive value supplementation of diet with various herbs is recommended. Thus also their analysis is of rising importance. While total elemental compositions are published for many common herbs, the origin of toxic as well as beneficial elements is not yet well investigated. Thus different indigenous medicinal plants, namely Croatian spruce (Picea abies), savory (Satureja montana L.), mountain yarrow (Achillea clavennae), showy calamint (Calamintha grandiflora), micromeria (Micromeria croatica), yellow gentian (Gentiana lutea) and fir (Abies alba) together with soil samples were collected in the National Park Northern Velebit. The macro- and trace elements content, after microwave digestion, was determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectroscopy (ICP-MS). The study focuses on the one hand on essential elements and on the other hand on non-essential elements which are considered as toxic for humans, covering in total Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sr and Zn.

Monitoring of Cu, Fe, Ni, and Zn in wastewater during treatment in a horizontal rotating tubular bioreactor.

The most appropriate systems for treatment of metal-contaminated waters are bioreactors with microbial biofilms. A horizontal rotating tubular bioreactor (HRTB) was studied for its applicability for removing copper, iron, nickel, and zinc (Cu, Fe, Ni, and Zn) from wastewater. Monitoring of the concentrations of Cu, Fe, Ni, and Zn by a fast, simple, onsite method was needed to make decisions for further optimization. The UV-VIS spectrophotometric quantification of Cu, Fe, Ni, and Zn using sodium diethyldithiocarbamate, 1,10-phenathroline, dimethylglyoxime, and 2-{[alpha-(2-Hydroxy-5-sulfophenylazo)-benzylidene]-hydrazino}-benzoic acid monosodium salt (=zincon monosodium salt) as reagents, respectively, was optimized and validated. The limits of quantification were 0.14, 0.12, 0.21, and 0.03 mg/L for Cu, Fe, Ni and Zn, respectively. The recovery for all elements was between 98 and 104%, the uncertainty of measurement was less than 6%. Depending on the reactor parameters applied, metal removals from 40 to more than 90% could be obtained.

Metal Characterization of White Hawthorn Organs and Infusions

Hawthorn is one of the most commonly used European and North American phytopharmaceuticals. Because there is no information on metals in seeds, and only rare data for leaves and flowers, the aim of the present study was elemental analysis of the white hawthorn (Crataegus monogyna) by inductively coupled plasma emission spectrometry (ICP-AES) or inductively coupled plasma mass spectrometry (ICP-MS) after digestion in a microwave-assisted system. The limits of detection are below 2 μg/g for ICP-AES and 0.5 μg/g for ICP-MS. Hawthorn leaves and flowers contain essential elements at concentrations (mean values, RSD 2-8%) in mg/g of Ca, 1-4; K, 4-5; Mg, 1-2; and Na, <0.2); and at μg/g levels of Ba, 1-10; Co, <0.16; Cr, <1.4; Cu, 0.6-7; Fe, 1-37; Li, <0.5; Mn, 1-13; Mo, <0.17; Ni, <0.6; Sr, 0.2-2; and Zn, 1-31. Toxic elements were found in low quantities: As (<0.04), Cd (0.04-0.1), and Pb (0.1-2). Up to 10% of the metals is extracted into the infusions. The analyzed plant parts and infusions contain essential elements justifying its use as a medicinal plant, whereas the low quantities of harmful elements will not pose any risk to humans when consumed.

Review – trace determination of potentially toxic elements in (medicinal) plant materials

Medicinal herbs are nowadays widely used as home remedies for a huge variety of ailments. As non-synthetic medicines, they are considered safe for human health. Due to metal uptake from soil via roots, from air via wet or dry deposition or by contamination during processing, plant materials may contain high amounts of harmful metals, such as arsenic, cadmium or lead. The World Health Organization (WHO) has thus established maximum concentration limits for these elements in order to ensure the safe use of herbs. Therefore, it is important to determine the current metal levels in herbs and their parts used for medical applications in order to determine any potential contamination. These concentrations are in the trace and ultra-trace range; thus analytical experience is needed for appropriate sampling, sample preparation, subsequent measurement by a suitable method and finally the evaluation and interpretation of the data obtained. In the presented review, possible sample preparation methods as well as analytical methods suitable for the given analytical task are summarized and discussed. Based on the sample matrix, the metals to be determined and their expected concentration range, and the sample preparation method as well as the subsequent analytical instrument have to be carefully chosen, optimized and validated.