A comparative study of interaction between chicken egg white lysozyme (Lyz) with two hexavalent chromate ions; chromate and dichromate; which are prevalently known for their toxicity, was investigated using different spectroscopic techniques along with a molecular docking study. Both steady-state and time-resolved studies revealed that the addition of chromate/dichromate is responsible for strong quenching of intrinsic fluorescence in Lyz and the quenching is caused by both static and dynamic quenching mechanisms. Different binding and thermodynamic parameters were also calculated at different temperatures from the intrinsic fluorescence of Lyz. The conformational change in Lyz and thermodynamic parameters obtained during the course of interaction with chromate/dichromate were well-supported by the molecular docking results.
- Klíčová slova
- Lyz, anisotropy, chromate, dichromate, fluorescence quenching,
- MeSH
- chromany * MeSH
- cirkulární dichroismus MeSH
- fluorescenční spektrometrie MeSH
- muramidasa * chemie MeSH
- simulace molekulového dockingu MeSH
- termodynamika MeSH
- vazba proteinů MeSH
- vazebná místa MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- chromany * MeSH
- muramidasa * MeSH
BACKGROUND: The master cast is the gold standard for the control and eventual adjustment of restorations produced by conventional procedures. Some digital workflow bypasses the master cast and relies completely on the precision of the CAD/CAM restoration. AIM: To examine the reproducibility of the margins of CAD/CAM restorations generated from a single digital scan. Also, to check the readiness of these restorations for delivery directly after fabrication without adjustment on a master cast and thereby eliminate the need for the master cast. METHODS: A total of 18 metal substructures made from cobalt chrome alloy were fabricated utilizing a single STL file. The circumference was divided into eight zones. The vertical marginal discrepancy (VMD) was measured at each zone of each metal substructure, with optical microscopy at ×200 magnification. RESULTS: Measurements of vertical marginal discrepancy were in a range of (-94: 300) with a mean of 62 ± 60 μm. A one-way ANOVA test revealed that the mean VMD is significantly different among the 18 substructures (F17, 1,134 = 63.948, p < 0.001). CONCLUSION: Although all the received substructures were fabricated from the same scan file, they were not identical and varied widely, and they were going outside the acceptable range in some zones. Within the limitations of this study, the marginal fit can be improved by extraoral adjustments on the master cast. Thus, skipping the master cast deprives the dentist of delivering a restoration of higher quality.
- Klíčová slova
- CAD/CAM, Digital impression, Digital workflow, Digitalization, Marginal adaptation, Marginal discrepancy, Marginal gap, Master cast, Metal coping, Metal substructures,
- MeSH
- analýza rozptylu MeSH
- design s pomocí počítače * MeSH
- mikroskopie * MeSH
- reprodukovatelnost výsledků MeSH
- slitiny chromu MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- slitiny chromu MeSH
This paper presents the results of water, soil and air analyses taken in the vicinity of a former ferrochromium metallurgical plant. In the past, the area was used for the disposal of waste materials containing smelter slag, dust and other waste products from the manufacture of ferrochromium alloys for the army. Recently, production was abandoned and a project aimed at the liquidation of the dump has been initiated. The project concentrates on the recovery of chromium remains and the utilization of the leftover material as a road construction aggregate. Based on the analyses of ground water, soil and air, a health risk caused by environmental pollution with chromium, especially with Cr(VI), was determined for residential and occupational scenarios. It was found that the level of chromium emissions to the environment constitutes a potential danger of toxic and carcinogenic cases in humans exposed to the emission in the affected area. An increased level in the hazard quotient has been observed in the case of occupational activities. As far as the mutagenic effects are concerned, the occupational inhalation exposure was found to be very high, which may raise extreme concern about carcinogenic risk.
- Klíčová slova
- Chromium, Environment pollution, Health hazard, Health risk,
- MeSH
- chrom analýza MeSH
- dítě MeSH
- dospělí MeSH
- hodnocení rizik MeSH
- hutnictví MeSH
- inhalační expozice analýza MeSH
- konstrukční materiály * MeSH
- látky znečišťující životní prostředí analýza MeSH
- lidé MeSH
- prach analýza MeSH
- pracovní expozice analýza MeSH
- průmyslový odpad MeSH
- slitiny chromu analýza MeSH
- vláda MeSH
- voda analýza MeSH
- Check Tag
- dítě MeSH
- dospělí MeSH
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Polsko MeSH
- Názvy látek
- chrom MeSH
- ferrochromium MeSH Prohlížeč
- látky znečišťující životní prostředí MeSH
- prach MeSH
- průmyslový odpad MeSH
- slitiny chromu MeSH
- voda MeSH
UNLABELLED: PURPOSE OF THE STUDY The alloplastic materials currently used for protective surface layers on implants were tested in vitro under microbiological laboratory conditions by contamination with microbial agents most frequently found in deep infection of total joint replacements. The objective was to find out how the resistance to bacterial colonisation was related to different surface finishes. MATERIAL AND METHODS Each of 14 samples of alloplastic material currently used in the manufacture of orthopaedic implants was inoculated with each of the group of microorganisms most frequently infecting joint replacements; these were Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Enterococcus faecalis and Escherichia coli. At 24 hours of incubation, biofilms produced on sample surfaces were collected, stained with crystalline violet and assessed by spectrophotometry. The average value of biofilm absorbances (AV595) for the group of microorganism tested was taken as a basic characteristic of each material sample indicating its sensitivity to bacterial. RESULTS Of the metal materials with smooth surface finish, Vitalium (AV595, 0.368) showed the lowest affinity to microbial colonisation; next was titanium (AV595, 0.459) and steel (AV595, 0.505). A significant increase in sensitivity to bacterial colonisation was recorded in all types of surface finish of steel (AV595, 0.571) and in titanium alloy with a rough surface texture (AV595, 0.737 to 1.676); p < 0.05. Porous titanium surfaces significantly increased material affinity to colonisation. DISCUSSION Our study had certain limitations concerning in vitro evaluation of porous surfaces that have high affinity to bacterial colonisation. Porous titanium, and its hydroxyapatite layer in particular, considerably promotes osteoblast colonisation of the surface as well as implant osseointegration in the bone bed. Microorganisms therefore have no room for surface colonisation. Problematic may remain the surface parts outside contact with bone that keep their affinity to bacterial colonisation. CONCLUSIONS The material of choice for cemented implants is Vitalium which, of all metal surfaces, has the lowest sensitivity to bacterial colonisation. The materials of choice for cementless implants are titanium alloys. However, an osteoactive surface not in contact with bone remains a problem. On the one hand, its roughness and porosity are crucial to good osseointegration, on the other hand, its affinity to bacterial colonisation is high. KEY WORDS: alloplastic material, biofilm, joint replacement infection.
- MeSH
- artroplastiky kloubů přístrojové vybavení MeSH
- biofilmy růst a vývoj MeSH
- biokompatibilní materiály škodlivé účinky chemie MeSH
- Enterococcus faecalis fyziologie MeSH
- Escherichia coli fyziologie MeSH
- infekce spojené s protézou mikrobiologie MeSH
- lidé MeSH
- povrchové vlastnosti MeSH
- protézy a implantáty škodlivé účinky MeSH
- Pseudomonas aeruginosa fyziologie MeSH
- Staphylococcus aureus fyziologie MeSH
- Staphylococcus epidermidis fyziologie MeSH
- testování materiálů MeSH
- titan chemie MeSH
- vitalium chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- biokompatibilní materiály MeSH
- titan MeSH
- vitalium MeSH
At ecosystems level, environmental parameters such as temperature, pH, dissolved oxygen concentration and intensity of UV radiation (UVR) have an important role on the efficiency of organisms' physiological and behavioral performances and consequently on the capacity of response to contaminants. Insignificant alterations of these parameters may compromise this response. In addition, these parameters can additionally alter chemical compounds by inducing their degradation, producing thereafter other metabolites. Understanding the combined effects of chemicals and environmental parameters is absolutely necessary for an adequate prediction of risk in aquatic environments. According to this scenario, this work aims at studying the combined toxicity of UVR and three xenobiotics: the biocide triclosan (TCS), the metal chromium (as potassium dichromate, PD) and the fungicide prochloraz (PCZ). To achieve this goal zebrafish (Danio rerio) embryos (3h post fertilization (hpf)) were exposed to several concentrations of each chemical combined with different UV intensities; mortality and eggs were recorded every 24h for the all test duration (96 h). Results showed different response patterns depending on the toxicant, stress levels and duration of exposure. The combination of UVR and TCS indicated a dose ratio deviation where synergism was observed when UVR was the dominant stressor (day 2). The combination of UVR and PD presented a dose level dependency at day 3 indicating antagonism at low stress levels, changing with time where at day 4, a dose ratio deviation showed statistically that synergism occurred at higher PD concentrations. Finally, UVR combined with PCZ indicated a dose ratio at day 3 and dose level deviation at day 4 of exposure, suggesting a synergistic response when PCZ is the dominant stressor in the combination. The obtained results in this study highlighted the importance of taking into account the possible interaction of stressors and time of exposure to better predict environmental risk.
- Klíčová slova
- Chromium, Combined effects, Danio rerio, Prochloraz, Triclosan, UV radiation,
- MeSH
- antiinfekční látky lokální toxicita MeSH
- chemické látky znečišťující vodu toxicita MeSH
- dánio pruhované MeSH
- dvojchroman draselný toxicita MeSH
- embryo nesavčí účinky léků účinky záření MeSH
- imidazoly toxicita MeSH
- průmyslové fungicidy toxicita MeSH
- triclosan toxicita MeSH
- ultrafialové záření * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- antiinfekční látky lokální MeSH
- chemické látky znečišťující vodu MeSH
- dvojchroman draselný MeSH
- imidazoly MeSH
- prochloraz MeSH Prohlížeč
- průmyslové fungicidy MeSH
- triclosan MeSH
Occupational exposure to hexavalent chromium (Cr(VI)) compounds is of concern in many Cr-related industries and their surrounding environment. Cr(VI) is a proven toxin and carcinogen. The Cr(VI) compounds are easily absorbed, can diffuse across cell membranes, and have strong oxidative potential. Despite intensive studies of Cr(VI) pro-oxidative effects, limited data exist on the influence of Cr(VI) on selenoenzymes thioredoxin reductase (TrxR) and glutathione peroxidase (GPx)-important components of antioxidant defense system. This study investigates the effect of Cr(VI) exposure on antioxidant defense status, with focus on these selenoenzymes, and on trace element homeostasis in an acute experiment in rat. Male Wistar rats (130-140g) were assigned to two groups of 8 animals: I. control; and II. Cr(VI) treated. The animals in Cr(VI) group were administered a single dose of K2Cr2O7 (20 mg /kg, intraperitoneally (ip)). The control group received saline solution. After 24 h, the animals were sacrificed and the liver and kidneys were examined for lipid peroxidation (LP; thiobarbituric acid reactive substances (TBARS) concentration), the level of reduced glutathione (GSH) and the activities of GPx-1, TrxR-1, and glutathione reductase (GR). Samples of tissues were also used to estimate Cr accumulation and alterations in zinc, copper, and iron levels. The acute Cr(VI) exposure caused an increase in both hepatic and renal LP (by 70%, p < 0.01 and by 15%, p < 0.05, respectively), increased hepatic GSH level and GPx-1 activity, and decreased renal GPx-1 activity. The activity of GR was not changed. A significant inhibitory effect of Cr(VI) was found on TrxR-1 activity in both the liver and the kidneys. The ability of Cr(VI) to cause TrxR inhibition could contribute to its cytotoxic effects. Further investigation of oxidative responses in different in vivo models may enable the development of strategies to protect against Cr(VI) oxidative damage.
- Klíčová slova
- Hexavalent chromium, antioxidant defense, oxidative stress, selenoenzymes, trace elements,
- MeSH
- antioxidancia metabolismus MeSH
- chrom toxicita MeSH
- dvojchroman draselný toxicita MeSH
- glutathion metabolismus MeSH
- glutathionreduktasa genetika metabolismus MeSH
- homeostáza účinky léků MeSH
- játra účinky léků metabolismus MeSH
- koncentrace vodíkových iontů MeSH
- krysa rodu Rattus MeSH
- látky reagující s kyselinou thiobarbiturovou metabolismus MeSH
- ledviny účinky léků metabolismus MeSH
- měď metabolismus MeSH
- oxidační stres účinky léků MeSH
- peroxidace lipidů účinky léků MeSH
- potkani Wistar MeSH
- stopové prvky farmakologie MeSH
- thioredoxin-disulfidreduktasa antagonisté a inhibitory metabolismus MeSH
- železo metabolismus MeSH
- zinek metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- antioxidancia MeSH
- chrom MeSH
- dvojchroman draselný MeSH
- glutathion MeSH
- glutathionreduktasa MeSH
- látky reagující s kyselinou thiobarbiturovou MeSH
- měď MeSH
- stopové prvky MeSH
- thioredoxin-disulfidreduktasa MeSH
- železo MeSH
- zinek MeSH
An advanced surface engineering process combining micro-texture with a plasma carburising process was produced on CoCrMo femoral head, and their tribological properties were evaluated by the cutting-edge pendulum hip joint simulator coupled with thin film colorimetric interferometry. FESEM and GDOES showed that precipitation-free C S-phase with a uniform case depth of 10μm was formed across the micro-textures after duplex treatment. Hip simulator tests showed that the friction coefficient was reduced by 20% for micro-metre sized texture, and the long-term tribological property of microtexture was enhanced by the C-supersaturated crystalline microstructure formed on the surface of duplex treated CoCrMo, thereby enhancing biotribological durability significantly. In-situ colorimetric interferometry confirmed that the maximum film thickness around texture area was 530nm, indicating that the additional lubricant during sliding motion might provide exceptional bearing life.
- Klíčová slova
- Biotribology, Colorimetric interferometry, Friction, Plasma carburising, Surface texturing, Wear,
- MeSH
- inženýrství metody MeSH
- kyčelní protézy * MeSH
- mechanické jevy MeSH
- plazmové plyny * MeSH
- povrchové vlastnosti MeSH
- studie proveditelnosti MeSH
- tření MeSH
- vitalium chemie MeSH
- vysoká teplota * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- plazmové plyny * MeSH
- vitalium MeSH
Bacteria-assisted bioremediation is widely recognized as a low-cost method to minimize the consequences of soil pollution with toxic metals originating from industrial sites. Strains used in bioremediation have to deal with high metal load via biosorption, reduction, bioprecipitation, metal sequestration, and/or chelation. Actinobacteria, and streptomycetes in particular, are considered a perspective group for bioremediation as natural soil inhabitants with extensive secondary metabolism. Nevertheless, there is no reference information on survival of the model streptomycetes in the presence of the most abundant metal pollutants. Also, there are no reports describing the selection approaches towards improvement of bioremediation properties. In this work, the resistance of Streptomyces coelicolor M145 and Streptomyces sioyaensis Lv81 to certain transition metals and their growth under different pH values are described for the first time. Spontaneous chromate-resistant S. sioyaensis Lv81-138 strain was selected in the course of this work. Strain Lv81-138 is the most efficient actinobacterial Cr(VI) reducer reported so far, capable of converting 12 mmol/L of Cr(VI) into Cr(III) in a medium supplemented with 50 mmol/L K2CrO4.
- MeSH
- bakteriální léková rezistence * MeSH
- biotransformace MeSH
- chromany metabolismus toxicita MeSH
- koncentrace vodíkových iontů MeSH
- kovy metabolismus toxicita MeSH
- kultivační média chemie MeSH
- látky znečišťující životní prostředí metabolismus toxicita MeSH
- mikrobiální viabilita účinky léků MeSH
- mutace * MeSH
- oxidace-redukce MeSH
- Streptomyces účinky léků růst a vývoj metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- chromany MeSH
- kovy MeSH
- kultivační média MeSH
- látky znečišťující životní prostředí MeSH
A set of 69 concentration-response curves from 5 acute ecotoxicity assays was fitted with a 2-parameter logistic equation. High correlation between values of regression parameters suggested similar slopes of the curves. This enabled derivation of the empirical single-parameter logistic equation with the sole median effective concentration (EC50) parameter. Such an equation might be useful in the evaluation of lower-quality (preliminary) experimental data and for the reduction of the number of test organisms and of testing costs.
- Klíčová slova
- Acute ecotoxicity assays, Concentration-response slope, EC50 calculation, Logistic model,
- MeSH
- Aliivibrio fischeri účinky léků MeSH
- Chlorophyta účinky léků MeSH
- Daphnia účinky léků MeSH
- dvojchroman draselný toxicita MeSH
- látky znečišťující životní prostředí toxicita MeSH
- logistické modely * MeSH
- referenční standardy MeSH
- testy akutní toxicity * normy MeSH
- živorodka MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- dvojchroman draselný MeSH
- látky znečišťující životní prostředí MeSH
The objective of our study was to determine the prevalence of contact hypersensitivity in asymptomatic Czech schoolchildren. We recruited 236 Prague asymptomatic schoolchildren for epicutaneous tests. The children were tested with European baseline series (25 allergens). A total of 218 children (114 boys and 104 girls) completed the study. Of these, 67 (30.7%) children had one or more positive reactions to tested allergens. Nickel, neomycin and potassium dichromate were the most prevalent allergens detected in our study. Our findings may support the notion that allergic contact sensitization in children is not so rare and children, especially those with chronic dermatitis, should be patch tested regularly.
- MeSH
- alergeny MeSH
- atopická dermatitida epidemiologie MeSH
- dítě MeSH
- dvojchroman draselný MeSH
- kontaktní dermatitida epidemiologie MeSH
- konzervační prostředky farmaceutické MeSH
- lidé MeSH
- mladiství MeSH
- náplasťové testy MeSH
- neomycin MeSH
- nikl MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika epidemiologie MeSH
- Názvy látek
- alergeny MeSH
- dvojchroman draselný MeSH
- konzervační prostředky farmaceutické MeSH
- neomycin MeSH
- nikl MeSH
