There is limited evidence regarding the exposure-effect relationship between lung-cancer risk and hexavalent chromium (Cr(VI)) or nickel. We estimated lung-cancer risks in relation to quantitative indices of occupational exposure to Cr(VI) and nickel and their interaction with smoking habits. We pooled 14 case-control studies from Europe and Canada, including 16 901 lung-cancer cases and 20 965 control subjects. A measurement-based job-exposure-matrix estimated job-year-region specific exposure levels to Cr(VI) and nickel, which were linked to the subjects' occupational histories. Odds ratios (OR) and associated 95% confidence intervals (CI) were calculated by unconditional logistic regression, adjusting for study, age group, smoking habits and exposure to other occupational lung carcinogens. Due to their high correlation, we refrained from mutually adjusting for Cr(VI) and nickel independently. In men, ORs for the highest quartile of cumulative exposure to CR(VI) were 1.32 (95% CI 1.19-1.47) and 1.29 (95% CI 1.15-1.45) in relation to nickel. Analogous results among women were: 1.04 (95% CI 0.48-2.24) and 1.29 (95% CI 0.60-2.86), respectively. In men, excess lung-cancer risks due to occupational Cr(VI) and nickel exposure were also observed in each stratum of never, former and current smokers. Joint effects of Cr(VI) and nickel with smoking were in general greater than additive, but not different from multiplicative. In summary, relatively low cumulative levels of occupational exposure to Cr(VI) and nickel were associated with increased ORs for lung cancer, particularly in men. However, we cannot rule out a combined classical measurement and Berkson-type of error structure, which may cause differential bias of risk estimates.

• MeSH
• chrom toxicita   analýza   MeSH
• lidé MeSH
• nádory plic * chemicky indukované   epidemiologie   MeSH
• nikl toxicita   analýza   MeSH
• pracovní expozice * škodlivé účinky   analýza   MeSH
• studie případů a kontrol MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• metaanalýza MeSH

• MeSH
• alergie * klasifikace   patologie   terapie   MeSH
• kožní nemoci etiologie   patologie   terapie   MeSH
• lidé MeSH
• nikl škodlivé účinky   MeSH
• poruchy fotosenzitivity patologie   terapie   MeSH
• pot MeSH
• šperky škodlivé účinky   MeSH
• sperma MeSH
• voda škodlivé účinky   MeSH
• ženská infertilita etiologie   terapie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• novinové články MeSH

Synthetic food colorants are extensively used across the globe regardless of the fact that they induce deleterious side effects when used in higher amounts. In this work, a novel electrochemical sensor based on nickel nanoparticles doped lettuce-like Co3O4 anchored graphene oxide (GO) nanosheets was developed for effective detection of sulfonated azo dye sunset yellow widely used as a food colorant. Hydrothermal synthesis was adopted for the preparation of lettuce-like spinel Co3O4 nanoparticles and Ni-Co3O4 NPs/GO nanocomposite was prepared using ecofriendly and economical sonochemical method. The prepared ternary nanocomposite meticulously fabricated on a screen-printed carbon electrode exhibited remarkable electrocatalytic activity towards sunset yellow determination. This is apparent from the resultant well-defined and intense redox peak currents of Ni-Co3O4 NPs/GO nanocomposite modified electrode at very low potentials. The developed sunset yellow sensor exhibited a high sensitivity of 4.16 μA μM-1 cm-2 and a nanomolar detection limit of 0.9 nM in the linear range 0.125-108.5 μM. Furthermore, experiments were conducted to affirm excellent stability, reproducibility, repeatability, and selectivity of proposed sensor. The practicality of sunset yellow determination using the developed sensor was analyzed in different varieties of food samples including jelly, soft drink, ice cream, and candy resulting in recovery in the range of 96.16%-102.56%.

• MeSH
• azosloučeniny analýza   MeSH
• elektrochemické techniky metody   MeSH
• grafit MeSH
• kobalt chemie   MeSH
• kovové nanočástice chemie   MeSH
• limita detekce MeSH
• lineární modely MeSH
• nanokompozity chemie   MeSH
• nikl chemie   MeSH
• oxid hlinitý chemie   MeSH
• oxid hořečnatý chemie   MeSH
• oxidy chemie   MeSH
• potravinářská barviva analýza   MeSH
• reprodukovatelnost výsledků MeSH
• Publikační typ
• časopisecké články MeSH

OBJECTIVES: This study aimed to assess the predictors of allergic sensitisation to titanium and nickel in patients undergoing orthodontic treatment. METHODS: A total of 250 patients undergoing orthodontic treatment were invited to participate, and 235 were analysed (67% females). A patch test was performed using nickel sulphate, titanium, titanium dioxide, titanium oxalate, titanium nitride, and petrolatum as control. In addition, clinical signs of the oral mucosa, gingiva, tongue, lips, and allergological history were assessed. RESULTS: The predictors of metal allergic sensitisation in patients undergoing orthodontic treatment were adult age (OR = 2.6; 95% CI: 1.2-5.5; p = 0.016), female sex (OR = 3.0; 95% CI: 1.1-7.9; p = 0.025), exfoliative cheilitis (OR = 4.8; 95% CI: 1.9-12.4; p = 0.001), history of contact hypersensitivity (OR = 7.0; 95% CI: 1.3-35.4; p = 0.025), history of contact hypersensitivity to metals (OR = 8.3; 95% CI: 1.4-50.2; p = 0.021), and piercings (OR = 5.4; 95% CI: 2.1-13.9; p = 0.001). When predictors were analysed separately for these two metals, titanium sensitisation predictors were contact hypersensitivity to metals and piercing, whereas nickel sensitisation predictors were age and piercing. CONCLUSION: A positive patch test alone cannot draw definite conclusions regarding allergy. However, metal allergies in patients with orthodontic appliances could be considered in cases of previous contact hypersensitivity, previous reactions to metals, exfoliative cheilitis, and piercing.

• MeSH
• alergie * epidemiologie   MeSH
• cheilitida * chemicky indukované   MeSH
• dospělí MeSH
• kontaktní dermatitida * MeSH
• lidé MeSH
• nikl škodlivé účinky   MeSH
• oxaláty MeSH
• titan MeSH
• vazelína MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Úvod a cíl: Fraktura nikl-titanových nástrojů v endodoncii je komplikace, se kterou se dříve nebo později v ordinaci setká většina stomatologů. Stojí za ní zejména dva základní mechanismy a těmi jsou překročení limitu cyklické únavy, překročení limitu torzní únavy a jejich vzájemná kombinace. Účelem tohoto článku je osvětlit mechanismus fraktury nikl-titanového endodontického nástroje na podkladě cyklické únavy, faktory ji ovlivňující a s tím spojenou problematiku laboratorního testování. Metodika: Vyhledávání literatury bylo provedeno pomocí PubMed (MEDLINE), ScienceDirect a databáze Wiley Online Library. K vyhledání literatury byla použita klíčová slova týkající se dané tematiky. Poté byla provedena selekce vhodných zdrojů. Mechanismus fraktury nástroje: Fraktura na podkladě cyklické únavy má tři základní fáze. Iniciace, což je časový úsek, kdy dochází k morfologickým změnám zejména na povrchu a těsně pod povrchem nástroje do vzniku primární praskliny. Poté dochází k jejímu postupnému růstu za vzniku charakteristických pruhů. Jakmile dojde k překročení limitu lomové houževnatosti, přichází na řadu definitivní selhání a separace části nástroje. Faktory ovlivňující frakturu: Jeden z nejpodstatnějších vlivů na vznik fraktury má kvalita slitiny. Rotační endodontické nástroje v dnešní době můžeme rozdělit podle struktury na nástroje s převahou martenzitu nebo austenitu. Z pohledu cyklické únavy jsou martenzitické nástroje výrazně odolnější než nástroje austenitické. Drsnost povrchu má z fyzikálního hlediska přímý vliv na vznik fraktury, jelikož nerovnosti slouží jako predispoziční místa pro koncentraci napětí. Důležitý vliv má i tvar nástroje, který pozitivně ovlivňuje rezistenci vůči cyklické únavě, pokud má nástroj menší průměr. S rostoucím obsahem průřezu nástroje se zvyšuje tahové napětí na jeho povrchu, a proto dochází k rychlejšímu selhání. Okolní teplota signifikantně ovlivňuje vlastnosti nástrojů. Vyšší teplota snižuje odolnost vůči cyklické únavě. Je třeba brát v úvahu, že se nástroj může v teplotě místnosti chovat diametrálně odlišně v porovnání s teplotou v kořenovém kanálku. Nesmíme zapomínat ani na parametry kořenového kanálku, které zásadním způsobem ovlivňují selhání nástroje. Velmi důležitý je také typ rotace nástroje v kořenovém kanálku. Z tohoto pohledu jednoznačně můžeme říct, že rotační mód zkracuje dobu rezistence nástroje v porovnání s těmi recipročními. Pro testování cyklické únavy dosud nebyl určen vhodný výplachový roztok. Závěr: Tematika selhání endodontických nástrojů na bázi cyklické únavy je velmi obsáhlá. Její vývoj a pochopení může pomoci výrobě odolnějších nástrojů, a tím minimalizovat přítomnost této komplikace v ordinaci praktického zubního lékaře.

Introduction and aim: The fracture of Ni-Ti instruments is a complication that most dentists will sooner or later encounter in the dental office. There are mainly two basic mechanisms behind it and these are exceeding the cyclic fatigue limit, exceeding the torsional fatigue limit and their mutual combination. The purpose of this article is to describe the fracture mechanism of a nickel-titanium endodontic instrument based on cyclic fatigue, the influencing factors and related issues of laboratory testing. Methods: Literature searches were performed using PubMed (MEDLINE), ScienceDirect and the Wiley Online Library database. Keywords related to the topic were used to search the literature. Then suitable sources were selected. Instrument fracture mechanism: A cyclic fatigue fracture consists of three basic phases. Initiation, which is the period of time when morphological changes occur, especially on the surface and subsurface of the instrument, until the formation of the primary crack. After that the crack gradually grows with the formation of characteristic striations. As soon as the fracture toughness limit is exceeded, it is time for final failure and separation of part of the instrument. Factors affecting fracture: One of the most significant effects on fracture formation has the quality of the alloy. Today, rotary endodontic instruments can be divided according to their structure into the instruments with a predominance of martensite or austenite. From the point of view of cyclic fatigue, martensitic instruments are significantly more durable than austenitic. From a physical point of view, surface roughness has a direct effect on fracture formation as surface irregularities serve as predisposing points for stress concentration. The shape of the instrument also has an important effect, as the smaller diameter of the instrument and its core has a positive effect on the resistance to cyclic fatigue. As the cross-section area of the instrument increases, the tensile strain on its surface increases, thus, a faster failure occurs. The ambient temperature significantly affects the properties of the instruments. Higher temperature reduces resistance to cyclic fatigue. It should be kept in mind that the instrument may behave diametrically differently at room temperature compared to the root canal temperature. We must also not forget the parameters of the root canal, which fundamentally affect the failure of the instrument. The type of instrument movement kinematics in the root canal is also very important. From this point of view, we can clearly say that the rotational mode reduces the instruments's resistence to cyclic fatigue compared to reciprocal ones. An ideal irrigant has not yet been identified for cyclic fatigue testing. Conclusion: The topic of failure of endodontic instruments based on cyclic fatigue is very extensive. Its development and understanding can help the production of more durable instruments and thus minimize the presence of this complication in a general dental office.

• Klíčová slova
• únava materiálu, fraktura NiTi nástroje v endodoncii,
• MeSH
• lidé MeSH
• nikl MeSH
• selhání zařízení * MeSH
• titan MeSH
• zubní nástroje * škodlivé účinky   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• přehledy MeSH

Persistent use of pesticides and animal manure in agricultural soils inadvertently introduced heavy metals and antibiotic/antibiotic resistance genes (ARGs) into the soil with deleterious consequences. The microbiome and heavy metal and antibiotic resistome of a pesticide and animal manure inundated agricultural soil (SL6) obtained from a vegetable farm at Otte, Eiyenkorin, Kwara State, Nigeria, was deciphered via shotgun metagenomics and functional annotation of putative ORFs (open reading frames). Structural metagenomics of SL6 microbiome revealed 29 phyla, 49 classes, 94 orders, 183 families, 366 genera, 424 species, and 260 strains with the preponderance of the phyla Proteobacteria (40%) and Actinobacteria (36%), classes Actinobacteria (36%), Alphaproteobacteria (18%), and Gammaproteobacteria (17%), and genera Kocuria (16%), Sphingobacterium (11%), and Brevundimonas (10%), respectively. Heavy metal resistance genes annotation conducted using Biocide and Metal Resistance Gene Database (BacMet) revealed the detection of genes responsible for the uptake, transport, detoxification, efflux, and regulation of copper, cadmium, zinc, nickel, chromium, cobalt, selenium, tungsten, mercury, and several others. ARG annotation using the Antibiotic Resistance Gene-annotation (ARG-ANNOT) revealed ARGs for 11 antibiotic classes with the preponderance of β-lactamases, mobilized colistin resistance determinant (mcr-1), macrolide-lincosamide-streptogramin (MLS), glycopeptide, and aminoglycoside resistance genes, among others. The persistent use of pesticide and animal manure is strongly believed to play a major role in the proliferation of heavy metal and antibiotic resistance genes in the soil. This study revealed that agricultural soils inundated with pesticide and animal manure use are potential hotspots for ARG spread and may accentuate the spread of multidrug resistant clinical pathogens.

• MeSH
• aminoglykosidy MeSH
• antibakteriální látky farmakologie   MeSH
• bakteriální geny MeSH
• beta-laktamasy genetika   MeSH
• chrom MeSH
• dezinficiencia * MeSH
• glykopeptidy MeSH
• hnůj mikrobiologie   MeSH
• kadmium MeSH
• kobalt MeSH
• kolistin MeSH
• linkosamidy MeSH
• makrolidy MeSH
• měď MeSH
• metagenomika MeSH
• mikrobiota * genetika   MeSH
• nikl MeSH
• pesticidy * farmakologie   MeSH
• půda chemie   MeSH
• půdní mikrobiologie MeSH
• rtuť * MeSH
• selen * MeSH
• streptograminy MeSH
• wolfram MeSH
• zinek MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

To explore the interaction effects of ciprofloxacin and ampicillin with nickel on the growth of bacteria, Staphylococcus aureus strain ATCC 29213, Enterococcus faecalis ATCC 29212 and Escherichia coli ATCC 25922 were used. Minimum inhibitory concentrations (MICs) were determined for nickel, ciprofloxacin and ampicillin, and the checkerboard method was used to assess their cumulative effects on bacterial growth. The interactions between the metal and antibiotics were assessed by the fractional inhibitory concentration (FIC). The MICs for ciprofloxacin and ampicillin were 0.31 and 1 mg/L for E. faecalis, 0.62 and 1 mg/L for S. aureus and 0.005 and 2.5 for E. coli, respectively. The MIC for nickel was 1000 mg/L for all bacteria. The FIC results for ciprofloxacin and nickel demonstrated an antagonistic effect of the two agents on the growth of E. coli and E. faecalis and an additive effect on S. aureus. The FICs for ampicillin and nickel demonstrated a synergistic effect on the growth of E. faecalis and E. coli. Different interactions of metals and antibiotics were observed depending on the bacteria and the type of antibiotic.

• MeSH
• ampicilin farmakologie   MeSH
• antibakteriální látky farmakologie   MeSH
• Bacteria MeSH
• ciprofloxacin * farmakologie   MeSH
• Escherichia coli MeSH
• ionty farmakologie   MeSH
• mikrobiální testy citlivosti MeSH
• nikl farmakologie   MeSH
• Staphylococcus aureus * MeSH
• Publikační typ
• časopisecké články MeSH

Shape memory alloys (SMA) are materials with specific electric, mechanic and thermal qualities originating in their microscopic structure and as such are used to design so-called Smart structures. In biomedicine, they are used mostly for their shape memory properties during intravasal surgery. The commonly used SMA material for biomedical purposes is Nitinol, a nickel-titanium alloy that exhibits, especially when annealed, among other properties also superelasticity and high resistivity with strain changes. This makes it suitable for usage in strain gauge sensors. In this work, NiTi annealed wires were used to create a strain gauge sensor, which exploits their unique properties. The properties of these sensors were then described using a climatic chamber, stretching device and a set of weights. Those properties were then compared to similar sensors, that are using different principles. The development, that followed, used these sensors in particular biomedical applications.

• MeSH
• automatizované zpracování dat metody   přístrojové vybavení   MeSH
• biomedicínské technologie MeSH
• biomedicínský výzkum MeSH
• chytré materiály analýza   škodlivé účinky   terapeutické užití   MeSH
• elektrická impedance MeSH
• kvantitativní vztahy mezi strukturou a aktivitou MeSH
• manometrie metody   přístrojové vybavení   MeSH
• nikl škodlivé účinky   terapeutické užití   MeSH
• slitiny s tvarovou pamětí * chemie   klasifikace   škodlivé účinky   MeSH
• titan škodlivé účinky   terapeutické užití   MeSH
• Publikační typ
• práce podpořená grantem MeSH
• přehledy MeSH

The liquid state NMR chemical shift of protons is a parameter frequently used to characterize host-guest complexes. Its theoretical counterpart, that is, the 1H NMR chemical shielding affected by the solvent (1H CS), may provide important insights into spatial arrangements of supramolecular systems, and it can also be reliably obtained for challenging cases of an aggregation of aromatic and antiaromatic molecules in solution. This computational analysis is performed for the complex of coronene and an antiaromatic model compound in acetonitrile by employing the GIAO-B3LYP-PCM approach combined with a saturated basis set. Predicted 1H CS values are used to generate volumetric data, whose properties are thoroughly investigated. The 1H CS isosurface, corresponding to a value of the proton chemical shift taken from a previous experimental study, is described. The presence of the 1H CS isosurface should be taken into account in deriving structural information about supramolecular hosts and their encapsulation of small molecules.

• MeSH
• acetonitrily chemie   MeSH
• difrakce rentgenového záření MeSH
• izotopy uhlíku MeSH
• magnetická rezonanční spektroskopie metody   MeSH
• makromolekulární látky MeSH
• nikl chemie   MeSH
• normální rozdělení MeSH
• polycyklické sloučeniny chemie   MeSH
• protonová magnetická rezonanční spektroskopie MeSH
• protony MeSH
• rozpouštědla chemie   MeSH
• železo chemie   MeSH
• Publikační typ
• časopisecké články MeSH

The human zinc transporter ZnT8 provides the granules of pancreatic β-cells with zinc (II) ions for assembly of insulin hexamers for storage. Until recently, the structure and function of human ZnTs have been modelled on the basis of the 3D structures of bacterial zinc exporters, which form homodimers with each monomer having six transmembrane α-helices harbouring the zinc transport site and a cytosolic domain with an α,β structure and additional zinc-binding sites. However, there are important differences in function as the bacterial proteins export an excess of zinc ions from the bacterial cytoplasm, whereas ZnT8 exports zinc ions into subcellular vesicles when there is no apparent excess of cytosolic zinc ions. Indeed, recent structural investigations of human ZnT8 show differences in metal binding in the cytosolic domain when compared to the bacterial proteins. Two common variants, one with tryptophan (W) and the other with arginine (R) at position 325, have generated considerable interest as the R-variant is associated with a higher risk of developing type 2 diabetes. Since the mutation is at the apex of the cytosolic domain facing towards the cytosol, it is not clear how it can affect zinc transport through the transmembrane domain. We expressed the cytosolic domain of both variants of human ZnT8 and have begun structural and functional studies. We found that (i) the metal binding of the human protein is different from that of the bacterial proteins, (ii) the human protein has a C-terminal extension with three cysteine residues that bind a zinc(II) ion, and (iii) there are small differences in stability between the two variants. In this investigation, we employed nickel(II) ions as a probe for the spectroscopically silent Zn(II) ions and utilised colorimetric and fluorimetric indicators for Ni(II) ions to investigate metal binding. We established Ni(II) coordination to the C-terminal cysteines and found differences in metal affinity and coordination in the two ZnT8 variants. These structural differences are thought to be critical for the functional differences regarding the diabetes risk. Further insight into the assembly of the metal centres in the cytosolic domain was gained from potentiometric investigations of zinc binding to synthetic peptides corresponding to N-terminal and C-terminal sequences of ZnT8 bearing the metal-coordinating ligands. Our work suggests the involvement of the C-terminal cysteines, which are part of the cytosolic domain, in a metal chelation and/or acquisition mechanism and, as now supported by the high-resolution structural work, provides the first example of metal-thiolate coordination chemistry in zinc transporters.

• MeSH
• beta-buňky metabolismus   MeSH
• diabetes mellitus 2. typu genetika   patologie   MeSH
• inzulin genetika   metabolismus   MeSH
• konformace proteinů, alfa-helix genetika   MeSH
• lidé MeSH
• molekulární konformace MeSH
• nikl chemie   MeSH
• proteinové domény genetika   MeSH
• transportní proteiny chemie   genetika   ultrastruktura   MeSH
• vztahy mezi strukturou a aktivitou * MeSH
• zinek chemie   MeSH
• zinkový transportér 8 chemie   genetika   ultrastruktura   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH