This study evaluated the effect of low-molecular weight chitosan on Staphylococcus epidermidis, a common colonizer of joint implants and other prosthetic devices. We have also attempted to elucidate its mechanism of action. Chitosan was found to be effective against both the planktonic and biofilm cells (MIC80 35-40 mg/L; MBIC80 40-150 mg/L), in contrast to the antibiotics erythromycin and tetracycline with no antibiofilm activity (MBIC80 not found). In combination, chitosan had an additive effect with antibiotics on suspension growth of S. epidermidis (FICi 0.7-1.0), and the combinatory action caused a complete inhibition of biofilm metabolic activity in some cases. In addition, chitosan caused rapid cellular damage and enhanced antihaemolytic activity of tetracycline in combination towards S. epidermidis biofilm cells. Chitosan efficiently inhibited S. epidermidis growth acting via cell membrane damage, yet the extent of antimicrobial and antibiofilm activities was quite strain-specific. It was proved to be a very efficient antimicrobial agent worth further examination as a potent candidate in pharmaceutical research. Apart from antimicrobial activity, it also acted as antivirulence enhancing agent which is a very promising strategy for alternative infectious diseases treatment.

• MeSH
• antibakteriální látky farmakologie   MeSH
• antiinfekční látky * MeSH
• biofilmy MeSH
• buněčná membrána MeSH
• chitosan * farmakologie   MeSH
• mikrobiální testy citlivosti MeSH
• molekulová hmotnost MeSH
• Staphylococcus epidermidis MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antibakteriální látky MeSH
• antiinfekční látky * MeSH
• chitosan * MeSH

Today, it is proven that the contaminated urban soils are hazardous for the human health. Soil substrates of playgrounds call for special research as they are places where children are directly exposed to soil contaminants. Therefore, the objective of this work was to measure the pseudo-total contents and bioaccessibility of several metals and metalloids (As, Bi, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Sn, V, Zn) in two grain sizes (< 150 μm and < 50 μm) of playground soils in Bratislava city (the capital of Slovakia). The content of metal(loid)s in the soils was controlled by a number of factors, with their increased contents (above 75% percentile or higher) at sites influenced by point sources of pollution (industry and agriculture) or at old sites located in the city centre. Cobalt, Cr, Fe, Mn, Ni and V had relatively uniform contents in soils compared to the other elements. As regression modelling with a categorical variable confirmed, the age of urban areas influenced the accumulation of As, Bi, Cd, Cu, Hg, Pb, Sb and Sn in playground soils. Exploratory statistical techniques with compositionally transformed data (principal component analysis, cluster analysis and construction of symmetric coordinates for correlation analysis) divided trace elements into the two main groupings, Co, Cr, Fe, Mn, Ni, V and Bi, Cd, Cu, Hg, Pb, Sb, Sn, Zn. Median concentrations of the elements in smaller soil grains (< 50 μm) were significantly higher than in coarser grains (< 150 μm). Cobalt, Cu, Mn, Pb, Sn and Zn had significantly higher bioaccessible proportions (% of the pseudo-total content) in < 50 μm soil size than in < 150 μm; however, the same order of bioaccessibility was achieved in both grain sizes. The highest bioaccessibility had Cd, Cu, Pb and Zn (~ 40% and more), followed by Co, As, Mn, Sb (18-27%), Hg, Ni, Sn (10-12%) and finally Cr, Fe and V (less than 4%). The hazard index and carcinogenic risk values were higher in < 50 μm than in < 150 μm and significantly decreased in the two soil sizes when the bioaccessibility results were included in the health hazard calculation.

• Klíčová slova
• Bioaccessibility, Contamination, Health risk assessment, Metal(loid)s, Urban soil,
• MeSH
• biologická dostupnost MeSH
• dítě MeSH
• karcinogeny analýza   MeSH
• kovy analýza   farmakokinetika   MeSH
• látky znečišťující půdu analýza   farmakokinetika   toxicita   MeSH
• lidé MeSH
• monitorování životního prostředí metody   MeSH
• polokovy analýza   farmakokinetika   MeSH
• půda chemie   MeSH
• stopové prvky analýza   farmakokinetika   toxicita   MeSH
• velikost částic MeSH
• velkoměsta MeSH
• veřejné parky MeSH
• vystavení vlivu životního prostředí škodlivé účinky   analýza   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Slovenská republika MeSH
• velkoměsta MeSH
• Názvy látek
• karcinogeny MeSH
• kovy MeSH
• látky znečišťující půdu MeSH
• polokovy MeSH
• půda MeSH
• stopové prvky MeSH

Pterostilbene (PTE), a dimethylated analogue of resveratrol, mostly contained in Vitis vinifera leaves or in other plant sources is well-known for its antioxidant activity. Due to its bioavailability, low hydrophilicity and thus ability to penetrate hydrophobic biological membranes it was found to be an antimicrobial agent. These properties of PTE offer the possibility of its use in the treatment of microbial infections. The emergence of antibiotic resistance of microorganisms is often caused by their ability to form biofilm; new substances with antibiofilm activity are therefore sought. The representatives of opportunistic pathogenic gram-positive and gram-negative bacteria as well as fungi were used for the determination of minimum inhibitory concentrations (MIC50 and MIC80), minimum biofilm inhibitory concentrations (MBIC50 and MBIC80) and minimum biofilm eradication concentrations (MBEC50 and MBEC80) of PTE and commonly used antibiotics erythromycin, polymyxin B or antimycotic amphotericin B. Total biofilm biomass was investigated by crystal violet staining, and the results were confirmed using microscopic techniques. The most significant antibiofilm action was proved for gram-positive cocci, e.g., MBEC50 of PTE for all strains of Staphylococcus epidermidis tested was 25 mg/L. By contrast, the antibiotic ERM did not exhibit antibiofilm activity in most cases. The permeabilization of cell membranes of gram-positive cocci biofilm by MBIC50 and MBEC50 of PTE was confirmed by LIVE/DEAD staining using spinning disc confocal microscopy. PTE significantly influenced the ability of gram-positive cocci to form biofilm and it effectively eradicated pre-formed biofilm in vitro; its potential for the treatment of biofilm-associated infections of Staphylococcus spp. or Enterococcus faecalis is thus apparent.

• Klíčová slova
• Antibiofilm, Biofilm inhibition, Eradication, Gram-positive cocci, Pterostilbene,
• MeSH
• antibakteriální látky farmakologie   MeSH
• antioxidancia farmakologie   MeSH
• biofilmy účinky léků   růst a vývoj   MeSH
• Enterococcus faecalis účinky léků   MeSH
• gramnegativní bakterie účinky léků   MeSH
• grampozitivní bakterie účinky léků   MeSH
• grampozitivní koky účinky léků   MeSH
• listy rostlin chemie   MeSH
• mikrobiální testy citlivosti MeSH
• Pseudomonas aeruginosa účinky léků   MeSH
• rostlinné extrakty farmakologie   MeSH
• Staphylococcus epidermidis účinky léků   MeSH
• stilbeny farmakologie   MeSH
• Vitis chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antibakteriální látky MeSH
• antioxidancia MeSH
• pterostilbene MeSH Prohlížeč
• rostlinné extrakty MeSH
• stilbeny MeSH

RATIONALE: Applications where stable C and O isotope compositions are useful require routine instrumental techniques with a fast sample throughput which should also produce accurate and precise results. We present a comparison of three different instrumental isotope ratio mass spectrometry (IRMS) approaches (Dual Inlet - DI; Elemental Analyzer - EA; Continuous Flow - CF) to determine the stable isotope composition of carbon in carbonate matrices, with a focus on evaluating the optimum approach for less complex instrumental techniques. METHODS: The DI-IRMS method is taken as an absolute method for obtaining accurate and precise 13 C/12 C ratios with internal errors usually < ±0.01‰ (2SD) and long-term reproducibility better than ±0.03‰ (2SD). The drawbacks of DI-IRMS are that it requires extensive offline sample preparation, rather large sample sizes (commonly >20 mg) and extended analysis times. RESULTS: EA-IRMS provides rapidity of analysis, relatively non-complex technique optimization and large sample throughput sufficient to distinguish natural trends although the larger internal errors and poorer reproducibility must be considered. The major disadvantage of EA-IRMS lies in a constant offset of the 13 C/12 C ratios against DI-IRMS, large internal errors (±0.2‰, 2SD) and the worst reproducibility (±0.3‰, 2SD) of all the explored methods. The results acquired using CF-IRMS are comparable with those obtained by employing DI-IRMS with an external reproducibility better than ±0.2‰ (2SD). Compared with EA-IRMS, however, this technique requires more elaborate sample preparation - more akin to DI-IRMS. None of these two latter techniques can provide C isotope results for coexisting phases such as calcite, dolomite and ankerite unless they are physically separated and analyzed independently. CONCLUSIONS: All methods are appropriate for 13 C/12 C determinations with CF-IRMS and EA-IRMS less applicable to high-precision measurements but relevant for studies requiring high sample throughput. Periodical analysis of matrix-matched reference materials during the analytical sequence is warranted for both EA-IRMS and CF-IRMS.

• Publikační typ
• časopisecké články MeSH

Microorganisms that cause chronic infections exist predominantly as surface-attached stable communities known as biofilms. Microbial cells in biofilms are highly resistant to conventional antibiotics and other forms of antimicrobial treatment; therefore, modern medicine tries to develop new drugs that exhibit anti-biofilm activity. We investigated the influence of a plant polyphenolic compound resveratrol (representative of the stilbene family) on the opportunistic pathogen Trichosporon cutaneum. Besides the influence on the planktonic cells of T. cutaneum, the ability to inhibit biofilm formation and to eradicate mature biofilm was studied. We have tested resveratrol as pure compound, as well as resveratrol in complex plant extract-the commercially available dietary supplement Regrapex-R-forte, which contains the extract of Vitis vinifera grape and extract of Polygonum cuspidatum root. Regrapex-R-forte is rich in stilbenes and other biologically active substances. Light microscopy imaging, confocal microscopy, and crystal violet staining were used to quantify and visualize the biofilm. The metabolic activity of biofilm-forming cells was studied by the tetrazolium salt assay. Amphotericin B had higher activity against planktonic cells; however, resveratrol and Regrapex-R-forte showed anti-biofilm effects, both in inhibition of biofilm formation and in the eradication of mature biofilm. The minimum biofilm eradicating concentration (MBEC80) for Regrapex-R-forte was found to be 2222 mg/L (in which resveratrol concentration is 200 mg/L). These methods demonstrated that Regrapex-R-forte can be employed as an anti-biofilm agent, as it has similar effect as amphotericin B (MBEC80 = 700 mg/L), which is routinely used in clinical practice.

• Klíčová slova
• Anti-biofilm activity, Plant extract, Stilbene, Trichosporon,
• MeSH
• amfotericin B farmakologie   MeSH
• antifungální látky farmakologie   MeSH
• biofilmy účinky léků   růst a vývoj   MeSH
• mikrobiální testy citlivosti MeSH
• resveratrol farmakologie   MeSH
• Reynoutria japonica chemie   MeSH
• rostlinné extrakty farmakologie   MeSH
• Trichosporon účinky léků   růst a vývoj   metabolismus   MeSH
• Vitis chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• amfotericin B MeSH
• antifungální látky MeSH
• resveratrol MeSH
• rostlinné extrakty MeSH

The laterite Ni ore smelting operations in Niquelândia and Barro Alto (Goiás State, Brazil) have produced large amounts of fine-grained smelting wastes, which have been stockpiled on dumps and in settling ponds. We investigated granulated slag dusts (n = 5) and fly ash samples (n = 4) with a special focus on their leaching behaviour in deionised water and on the in vitro bioaccessibility in a simulated gastric fluid, to assess the potential exposure risk for humans. Bulk chemical analyses indicated that both wastes contained significant amounts of contaminants: up to 2.6 wt% Ni, 7580 mg/kg Cr, and 508 mg/kg Co. In only one fly ash sample, after 24 h of leaching in deionised water, the concentrations of leached Ni exceeded the limit for hazardous waste according to EU legislation, whereas the other dusts were classified as inert wastes. Bioaccessible fractions (BAF) of the major contaminants (Ni, Co, and Cr) were quite low for the slag dusts and accounted for less than 2 % of total concentrations. In contrast, BAF values were significantly higher for fly ash materials, which reached 13 % for Ni and 19 % for Co. Daily intakes via oral exposure, calculated for an adult (70 kg, dust ingestion rate of 50 mg/day), exceeded neither the tolerable daily intake (TDI) nor the background exposure limits for all of the studied contaminants. Only if a higher ingestion rate is assumed (e.g. 100 mg dust per day for workers in the smelter), the TDI limit for Ni recently defined by European Food Safety Authority (196 µg/day) was exceeded (324 µg/day) for one fly ash sample. Our data indicate that there is only a limited risk to human health related to the ingestion of dust materials generated by laterite Ni ore smelting operations if appropriate safety measures are adopted at the waste disposal sites and within the smelter facility.

• Klíčová slova
• Bioaccessibility, Dust, Fly ash, Laterite, Ni smelting, Slag,
• MeSH
• anorganické látky aplikace a dávkování   MeSH
• aplikace orální MeSH
• biologické modely MeSH
• chrom analýza   MeSH
• hutnictví * MeSH
• kobalt analýza   MeSH
• lidé MeSH
• nebezpečný odpad analýza   MeSH
• nikl analýza   MeSH
• odpadky - odstraňování metody   MeSH
• popel uhelný analýza   MeSH
• prach analýza   MeSH
• průmyslový odpad MeSH
• vystavení vlivu životního prostředí * MeSH
• žaludeční šťáva MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Brazílie MeSH
• Názvy látek
• anorganické látky MeSH
• chrom MeSH
• kobalt MeSH
• nebezpečný odpad MeSH
• nikl MeSH
• popel uhelný MeSH
• prach MeSH
• průmyslový odpad MeSH

Heterogeneous catalysts based on materials with permanent porosity are of great interest owing to their high specific surface area, easy separation, recovery, and recycling ability. Additionally, porous polymer catalysts (PPCs) allow us to tune catalytic activity by introducing various functional centres. This study reports the preparation of PPCs with a permanent micro/mesoporous texture and a specific surface area SBET of up to 1000 m2 g-1 active in acid-catalyzed reactions, namely aldehyde and ketone acetalization and carboxylic acid esterification. These PPC-type conjugated hyper-cross-linked polyarylacetylene networks were prepared by chain-growth homopolymerization of 1,4-diethynylbenzene, 1,3,5-triethynylbenzene and tetrakis(4-ethynylphenyl)methane. However, only some ethynyl groups of the monomers (from 58 to 80 %) were polymerized into the polyacetylene network segments while the other ethynyl groups remained unreacted. Depending on the number of ethynyl groups per monomer molecule and the covalent structure of the monomer, PPCs were decorated with unreacted ethynyl groups from 3.2 to 6.7 mmol g-1 . The hydrogen atoms of the unreacted ethynyl groups served as acid catalytic centres of the aforementioned organic reactions. To the best of our knowledge, this is first study describing the high activity of hydrogen atoms of ethynyl groups in acid-catalyzed reactions.

• Klíčová slova
• acetalization, hyper-cross-linked polymers, microporous polymers, polyacetylenes, porous polymer catalysts,
• Publikační typ
• časopisecké články MeSH

Microbial adhesion to surfaces and the subsequent biofilm formation may result in contamination in food industry and in healthcare-associated infections and may significantly affect postoperative care. Some plants produce substances with antioxidant and antimicrobial properties that are able to inhibit the growth of food-borne pathogens. The aim of our study was to evaluate antimicrobial and anti-biofilm effect of baicalein, resveratrol, and pterostilbene on Candida albicans, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli. We determined the minimum inhibitory concentrations (MIC), the minimum adhesion inhibitory concentration (MAIC), and the minimum biofilm eradication concentration (MBEC) by crystal violet and XTT determination. Resveratrol and pterostilbene have been shown to inhibit the formation of biofilms as well as to disrupt preformed biofilms. Our results suggest that resveratrol and pterostilbene appear potentially very useful to control and inhibit biofilm contaminations by Candida albicans, Staphylococcus epidermidis, and Escherichia coli in the food industry.

• Klíčová slova
• Adhesion, Baicalein, Biofilm, Eradication, Pterostilbene, Resveratrol,
• MeSH
• antiinfekční látky farmakologie   MeSH
• biofilmy účinky léků   růst a vývoj   MeSH
• Candida albicans účinky léků   růst a vývoj   MeSH
• Escherichia coli účinky léků   růst a vývoj   MeSH
• flavanony farmakologie   MeSH
• mikrobiální testy citlivosti MeSH
• Pseudomonas aeruginosa účinky léků   růst a vývoj   MeSH
• resveratrol MeSH
• rostlinné extrakty chemie   farmakologie   MeSH
• Staphylococcus epidermidis účinky léků   růst a vývoj   MeSH
• stilbeny farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antiinfekční látky MeSH
• baicalein MeSH Prohlížeč
• flavanony MeSH
• pterostilbene MeSH Prohlížeč
• resveratrol MeSH
• rostlinné extrakty MeSH
• stilbeny MeSH