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1.
J Can Dent Assoc ; 87: l1, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-34343064

RESUMO

OBJECTIVE: To investigate pedagogical approaches and perceived barriers to teaching about caries-control medications, particularly silver diamine fluoride (SDF), in Canadian undergraduate dental and dental hygiene programs. METHODS: In summer 2018, a 9-item questionnaire was distributed to all 10 dental schools and 32 dental hygiene programs in Canada. It enquired about the types of caries-control medications used, teaching methods and perceived barriers to instruction on managing active caries with SDF. METHODS: In summer 2018, a 9-item questionnaire was distributed to all 10 dental schools and 32 dental hygiene programs in Canada. It enquired about the types of caries-control medications used, teaching methods and perceived barriers to instruction on managing active caries with SDF. RESULTS: The response rate was 80% (n = 8) from dental schools and 72% (n = 23) from dental hygiene programs. All curricula included information about conventional caries-control medications: fluoride, silver nitrate and povidone iodine. In all programs, instruction regarding SDF was predominantly didactic: 93% of programs presented lectures on SDF and 30% of programs included clinical teaching and use of SDF in primary dentition only. The lack of consensus on clinical protocols outlining the number and frequency of SDF applications to arrest caries was cited by 43% of the programs as a barrier to clinical teaching. CONCLUSION: There is some variation across Canada in pedagogical approaches to caries-control medications and the inclusion of SDF in curricula. Poorly defined clinical protocols were reported as the main barrier to didactic and clinical use of SDF in undergraduate dental education programs.


Assuntos
Cárie Dentária , Higiene Bucal , Canadá , Cárie Dentária/tratamento farmacológico , Cárie Dentária/prevenção & controle , Suscetibilidade à Cárie Dentária , Fluoretos Tópicos , Humanos , Nitrato de Prata
2.
Biomolecules ; 11(6)2021 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-34207836

RESUMO

Environmental plastic wastes are continuously degraded to their micro and nanoforms. Since in the environment they coexist with other pollutants, it has been suggested that they could act as vectors transporting different toxic trace elements, such as metals. To confirm this, we have assessed the potential interactions between nanopolystyrene, as a model of nanoplastic debris, and silver compounds (silver nanoparticles and silver nitrate), as models of metal contaminant. Using TEM-EDX methodological approaches, we have been able to demonstrate metal sorption by nanopolystyrene. Furthermore, using Caco-2 cells and confocal microscopy, we have observed the co-localization of nanopolystyrene/nanosilver in different cellular compartments, including the cell nucleus. Although the internalization of these complexes showed no exacerbated cytotoxic effects, compared to the effects of each compound alone, the silver/nanopolystyrene complexes modulate the cell's uptake of silver and slightly modify some harmful cellular effects of silver, such as the ability to induce genotoxic and oxidative DNA damage.


Assuntos
Nanopartículas Metálicas/toxicidade , Microplásticos/efeitos adversos , Poliestirenos/toxicidade , Transporte Biológico , Células CACO-2 , Dano ao DNA/efeitos dos fármacos , Humanos , Intestinos/efeitos dos fármacos , Microplásticos/química , Nanopartículas/toxicidade , Nanoestruturas/química , Nanoestruturas/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Poliestirenos/química , Prata/farmacologia , Nitrato de Prata/farmacologia
3.
Chemosphere ; 283: 131164, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34144291

RESUMO

Limited studies of quantitative toxicity-toxicity relationship (QTTR) modeling have been conducted to predict interspecies toxicity of engineered nanomaterials (ENMs) between aquatic test species. A meta-analysis of 66 publications providing acute toxicity data of silver nanoparticles (AgNPs) to daphnia and fish was performed, and the toxicity data, physicochemical properties, and experimental conditions were collected and curated. Based on Euclidean distance (ED) grouping, a meaningful correlation of logarithmic lethal concentrations between daphnia and fish was derived for bare (R2bare = 0.47) and coated AgNPs (R2coated = 0.48) when a distance of 10 was applied. The correlation of coated AgNPs was improved (R2coated = 0.55) by the inclusion of descriptors of the coating materials. The correlations were further improved by R2bare = 0.57 and R2coated = 0.81 after additionally considering particle size only, and by R2bare = 0.59 and R2coated = 0.92 after considering particle size and zeta potential simultaneously. The developed ED-based nano-QTTR model demonstrated that inclusion of the coating material descriptors and physicochemical properties improved the goodness-of-fit to predict interspecies aquatic toxicity of AgNPs between daphnia and fish. This study provides insight for future in silico research on QTTR model development in ENM toxicology.


Assuntos
Daphnia , Nanopartículas Metálicas , Animais , Nanopartículas Metálicas/toxicidade , Tamanho da Partícula , Prata/toxicidade , Nitrato de Prata
4.
Molecules ; 26(9)2021 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-34066875

RESUMO

The main core of wound treatment is cell growth and anti-infection. To accelerate the proliferation of fibroblasts in the wound and prevent wound infections, various strategies have been tried. It remains a challenge to obtain good cell proliferation and antibacterial effects. Here, human hair kerateine (HHK)/poly(ethylene oxide) (PEO)/poly(vinyl alcohol) (PVA) nanofibers were prepared using cysteine-rich HHK, and then, silver nanoparticles (AgNPs) were in situ anchored in the sulfur-containing amino acid residues of HHK. After the ultrasonic degradation test, HHK/PEO/PVA nanofibrous mats treated with 0.005-M silver nitrate were selected due to their relatively complete structures. It was observed by TEM-EDS that the sulfur-containing amino acids in HHK were the main anchor points of AgNPs. The results of FTIR, XRD and the thermal analysis suggested that the hydrogen bonds between PEO and PVA were broken by HHK and, further, by AgNPs. AgNPs could act as a catalyst to promote the thermal degradation reaction of PVA, PEO and HHK, which was beneficial for silver recycling and medical waste treatment. The antibacterial properties of AgNP-HHK/PEO/PVA nanofibers were examined by the disk diffusion method, and it was observed that they had potential antibacterial capability against Gram-positive bacteria, Gram-negative bacteria and fungi. In addition, HHK in the nanofibrous mats significantly improved the cell proliferation of NIH3T3 cells. These results illustrated that the AgNP-HHK/PEO/PVA nanofibrous mats exhibited excellent antibacterial activity and the ability to promote the proliferation of fibroblasts, reaching our target applications.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Proliferação de Células/efeitos dos fármacos , Queratinas Específicas do Cabelo/química , Nanopartículas Metálicas/química , Nanofibras/química , Polietilenoglicóis/química , Álcool de Polivinil/química , Prata/química , Animais , Candida albicans/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Cabelo/química , Humanos , Ligação de Hidrogênio , Camundongos , Testes de Sensibilidade Microbiana , Células NIH 3T3 , Nitrato de Prata/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Cicatrização/efeitos dos fármacos
6.
Braz J Biol ; 82: e237604, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34105671

RESUMO

This study goal to evaluate the effects of different concentrations of lead (Pb) and silver (Ag) on germination, initial growth and anatomical alterations of Lactuca sativa L. Plants use various mechanisms to reduce the impacts caused by anthropic action, such as xenobiotic elements of soils and water contaminated by heavy metals. These metals were supplied as lead nitrate and silver nitrate and the following treatments were established: control for both metals, maximum dose of heavy metals, for arable soils, allowed by the National Council of the Environment (Ag = 25 mg. Kg-1, Pb = 180 mg. Kg-1), double (Ag = 50 mg. Kg-1, Pb = 360 mg. Kg-1) and triple (Ag = 75 mg. Kg-1, Pb = 540 mg. Kg -1) of this dosage. Vigor and germination tests of the seeds and possible anatomical changes in the leaves and roots of lettuce plants were performed. The species showed a high capacity to germinate under Pb and Ag stress, and the germination was never completely inhibited; however, the germination decreased with increasing Pb concentrations, but not under Ag stress. The use of increasing doses of metals reduced seed vigor and increased chlorophyll content. An increase in biomass was also observed in plants from treatments submitted to Pb. The phytotoxic effects of metals were more pronounced at 15 days after sowing. Anatomically, L. sativa was influenced by metal concentrations, and had a reduction of up to 79.9% in root epidermis thickness at the highest Pb concentration, although some structures did not suffer significant changes. The results suggest that L. sativa presents tolerance to high concentrations of heavy metals, showing possible mechanisms to overcome the stress caused by these metals. In this research lettuce possibly used the mechanism of exclusion of metals retaining Pb and Ag in the roots preserving the photosynthetic apparatus in the aerial part of the plants. In general, the chemical element Pb was more toxic than Ag, in these experimental conditions.


Assuntos
Metais Pesados , Poluentes do Solo , Chumbo/toxicidade , Alface , Metais Pesados/análise , Metais Pesados/toxicidade , Nitratos/toxicidade , Nitrato de Prata , Solo , Poluentes do Solo/toxicidade
7.
Nat Commun ; 12(1): 3331, 2021 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-34099682

RESUMO

The rapid emergence of drug resistant Staphylococcus aureus (S. aureus) poses a serious threat to public health globally. Silver (Ag)-based antimicrobials are promising to combat antibiotic resistant S. aureus, yet their molecular targets are largely elusive. Herein, we separate and identify 38 authentic Ag+-binding proteins in S. aureus at the whole-cell scale. We then capture the molecular snapshot on the dynamic action of Ag+ against S. aureus and further validate that Ag+ could inhibit a key target 6-phosphogluconate dehydrogenase through binding to catalytic His185 by X-ray crystallography. Significantly, the multi-target mode of action of Ag+ (and nanosilver) endows its sustainable antimicrobial efficacy, leading to enhanced efficacy of conventional antibiotics and resensitization of MRSA to antibiotics. Our study resolves the long-standing question of the molecular targets of silver in S. aureus and offers insights into the sustainable bacterial susceptibility of silver, providing a potential approach for combating antimicrobial resistance.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana/efeitos dos fármacos , Nanopartículas Metálicas/química , Prata/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Cristalografia por Raios X , Staphylococcus aureus Resistente à Meticilina , Testes de Sensibilidade Microbiana , Fosfogluconato Desidrogenase/efeitos dos fármacos , Proteômica , Prata/química , Nitrato de Prata , Infecções Estafilocócicas
8.
Ecotoxicology ; 30(6): 1216-1226, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34046816

RESUMO

Microplastic fibers (MF) are released from synthetic textiles during washing and end up in the wastewater. Similarly, silver nanoparticles (AgNP), incorporated in textiles as antimicrobial agents, are released in washing machines, also reaching the wastewater treatment plants. Therefore, both MF and AgNP co-exist in the environment and enter the soil compartment mainly via the application of biosolids. Yet, the combined effect of MF and AgNP has not been studied. Here, we assessed the effects of polyester MF on the toxicity of AgNP and AgNO3 to the earthworm Eisenia andrei and the enchytraeid Enchytraeus crypticus. The organisms were exposed to a range of concentration of AgNP (32, 100, 320, 1000, 3200 mg Ag/kg) and AgNO3 (12.8, 32, 80, 200, 500 mg Ag/kg) in LUFA 2.2 soil in the absence or presence of MF (0.01% DW). Reproduction tests were conducted and the toxicity outcomes compared between soils with and without MF. The exposure to MF caused a decrease in the number of juveniles and changed the biochemical composition of earthworms. Moreover, the presence of MF increased the toxicity of AgNP to earthworm reproduction (EC50 = 165 mg Ag/kg) when compared to AgNP exposure alone (EC50 = 450 mg Ag/kg), but did not alter the toxicity of AgNO3 (EC50 = 40 mg Ag/kg). For enchytraeids, no significant difference in Ag toxicity could be detected when MF was added to the soil for both AgNP and AgNO3. Overall, Ag bioaccumulation was not affected by MF, except for a decrease in earthworm body concentration at the highest Ag soil concentration (3200 mg Ag/kg). Our results suggest that the presence of MF in the soil compartment may be a cause of concern, and that the joint exposure to Ag may be deleterious depending on the Ag form, organism, and endpoint. The present work provides the first evidence that a realistic MF concentration in soil lowers AgNP concentration necessary to provoke reproductive impairment in earthworms. The influence of MF on the risk assessment of AgNP should be considered.


Assuntos
Nanopartículas Metálicas , Oligoquetos , Poluentes do Solo , Animais , Bioacumulação , Nanopartículas Metálicas/toxicidade , Microplásticos , Plásticos/toxicidade , Prata/toxicidade , Nitrato de Prata/toxicidade , Solo , Poluentes do Solo/toxicidade
9.
J Laryngol Otol ; 135(6): 545-546, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33998426

RESUMO

BACKGROUND: This technical note describes a novel method of cauterising the posterior nasal cavity through the use of a plastic straw and silver nitrate. OBJECTIVE: This technique aims to prevent unwanted damage to surrounding nasal mucosa. METHODS: Once the nasal cavity has been prepared for cauterisation, the silver nitrate stick is navigated to the bleeding point covered by the plastic straw. The silver nitrate stick is then advanced onto the bleeding point allowing precise cauterisation of the nasal mucosa, without effecting surrounding healthy mucosa.


Assuntos
Cauterização/instrumentação , Cauterização/métodos , Cavidade Nasal/cirurgia , Nitrato de Prata , Desenho de Equipamento , Humanos
10.
Int J Biol Macromol ; 182: 2003-2018, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34029584

RESUMO

The presence of saccharin (SH) could be efficiently sensed (in the concentration range of 5 × 10-5 M to 5 × 10-1 M) through the interference synthesis of gum ghatti (GG) capped silver nanoparticles (GGAgNps). The synthesis used sodium borohydride and gum ghatti (GG) as the reducing and capping agents respectively. The strong hydrogen-bonding recognition between GG and SH was responsible for the interference. The intensity of the SPR peak of GGAgNps was found linearly dependent on [SH]. The SH detection was further enhanced when combo capping comprising of GG and chitosan (Ch) (in 1:1 weight ratio) was used while the use of gum acacia (GA) in place of Ch (in combo) decreased the detection sensitivity. The combo polysaccharide solutions had non-Newtonian behaviour and shear thinning property like GG. The method was also applied for the successful detection of SH in commercially available real juice samples.


Assuntos
Nanopartículas Metálicas/química , Gomas Vegetais/química , Sacarina/análise , Prata/química , Boroidretos/química , Concentração de Íons de Hidrogênio , Nanopartículas Metálicas/ultraestrutura , Tamanho da Partícula , Polissacarídeos/química , Nitrato de Prata/química , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Edulcorantes/análise , Fatores de Tempo , Viscosidade
11.
J Nanosci Nanotechnol ; 21(11): 5414-5428, 2021 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-33980351

RESUMO

In order to understand toxicity of nano silver, human hepatocellular carcinoma (HepG2) cells were treated either with silver nitrate (AgNO3) or with nano silver capped with glutathione (Ag-S) at various concentration. Differentially expressed genelists for mRNA and microRNA were obtained through Illumina RNA sequencing and DEseq data analyses. Both treatments showed non-linear dose response relationships for mRNA and microRNA. Gene expression analysis showed signaling pathways common to both nano Ag-S and AgNO3, such as cell cycle regulation, DNA damage response and cancer related pathways. But, nano Ag-S caused signaling pathway changes that were not altered by AgNO3 such as NRF2-mediated oxidative stress response inflammation, cell membrane signaling, and cell proliferation. Nano Ag-S also affected p53 signaling, survival, apoptosis, tissue repair, lipid synthesis, angiogenesis, liver fibrosis and tumor development. Several of the pathways affected by nano Ag-S are hypothesized as major contributors to nanotoxicity. MicroRNA target filter analysis revealed additional affected pathways that were not reflected in the mRNA expression response alone, including DNA damage signaling, genomic stability, ROS, cell cycle, ubiquitination, DNA methylation, cell proliferation and fibrosis for AgNO3; and cell cycle regulation, P53 signaling, cell proliferation, survival, apoptosis, tissue repair and so on for nano Ag-S. These pathways may be mediated by microRNA repression of protein translation.Our study clearly showed that the addition of microRNA profiling increased the numbers of signaling pathways discovered that affected by the treatments on HepG2 cells and gave US a better picture of the effects of these reagents in the cells.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Nanopartículas Metálicas , MicroRNAs , Carcinoma Hepatocelular/tratamento farmacológico , Carcinoma Hepatocelular/genética , Humanos , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/genética , Nanopartículas Metálicas/toxicidade , MicroRNAs/genética , RNA Mensageiro/genética , Prata/toxicidade , Nitrato de Prata/toxicidade
12.
Bull Environ Contam Toxicol ; 107(3): 421-426, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33974084

RESUMO

Silver nanoparticles (AgNP) are unique because of their biocide properties. Once released to environment, AgNP interact with the natural organic matter which impact on their fate, dispersion, and ultimate toxicity. We carried out an ex vivo exposure of gill of Corydoras paleatus fish to 100 µg L-1 of AgNP or AgNO3, alone and in combination with 10 mg L-1 of humic acids (HA), with the aim to evaluate the potential mitigation of HA on AgNP toxic effects. We analyzed Ag accumulation and oxidative stress biomarkers. The results showed high bioaccumulation after the AgNO3+HA exposure. An inhibition of glutathione-S-transferase enzymatic activity and depletion of reduced glutathione levels were registered after the AgNO3 exposure, and increased lipid peroxidation levels in the case of AgNP one. Oxidative responses were mitigated when the HA were present in the media. Overall, the knowledge about the fate of this emergent pollutant was deepened through this study.


Assuntos
Nanopartículas Metálicas , Nitrato de Prata , Animais , Brânquias , Substâncias Húmicas , Nanopartículas Metálicas/toxicidade , Prata/toxicidade , Nitrato de Prata/toxicidade
13.
Carbohydr Polym ; 262: 117714, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33838789

RESUMO

The laccase/TEMPO system was employed to oxidise the C6 primary hydroxyl group on the chitosan (CS) to form a carboxyl group to obtain oxidised chitosan (C-COS). The silver-oxidised chitosan complex(C-COS-Ag) was prepared by reacting C-COS with silver nitrate, then C-COS-Ag and cotton fibres were subjected to a reaction to prepare bacteriostatic fibres. FT-IR and XPS analysis showed that: Ag+ and C-COS were combined in these forms: Ag, [Ag(NH3)2] OH, -COOAg, and Ag2O. C-COS-Ag was combined with cotton fibres by way of ester bonds. The inhibition zone of bacteriostatic fibres was all greater than 11 mm. After 50 washing tests, the bacteriostatic effect of bacteriostatic fibres remained at above 99 %. The amount of silver ions that had migrated from the bacteriostatic fibre was 3.336 mg/kg.


Assuntos
Antibacterianos/farmacologia , Quitosana/química , Fibra de Algodão , Nanopartículas Metálicas/química , Prata/química , Antibacterianos/química , Óxidos N-Cíclicos , Humanos , Radical Hidroxila , Lacase , Oxirredução , Prata/farmacologia , Nitrato de Prata/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
14.
Int J Biol Macromol ; 181: 990-1002, 2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-33864870

RESUMO

Coronaviruses (CoV) are a large family of viruses that cause illness ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS-CoV). We succeeded in preparing disinfectant cellulose-based wipes treated with antimicrobial and antiviral silver nanoparticles to be used for prevention of contamination and transmission of several pathogenic viruses and microbes to human in critical areas such as hospitals and healthcare centers especially coronavirus. In this work, the antimicrobial and antiviral activities of silver nanoparticles (AgNPs) prepared with four different techniques were investigated for the utilization as a disinfectant for cellulose-based wipes. These four methods are namely; 1) trisodium citrate with cotton yarn as a reducing agent, 2) preparing AgNP's using aqueous solution of PVA in the presence of glucose, 3) trisodium citrate with cotton fabric as a reducing agent, and 4) photochemical reaction of polyacrylic acid and silver nitrate solution. Polyester/viscose blended spunlace nonwoven fabrics as cellulose based fabrics were treated with the prepared silver nanoparticles to be used as surfaces disinfection wipes. The properties of the nonwoven fabrics were examined including thickness, tensile strength in dry and wet conditions in both machine direction (MD) and cross-machine direction (CMD), bursting strength, air permeability, water permeability and surface wettability. Characterization of the AgNPs was carried out in terms of UV-VIS spectroscopy, TEM, SEM, and Zeta potential analysis. The assessment of AgNPs active solutions for antimicrobial and antiviral activities was evaluated. The results obtained from the analyses of the AgNPs samples prepared with different techniques showed good uniformity and stability of the particles, as well uniform coating of the AgNPs on the fibers. Additionally, there is a significant effect of the AgNPs preparation method on their disinfectant performance that proved its effectiveness against coronavirus (MERS-CoV), S. aureus and B. subtilis as Gram-positive bacteria, E. coli and P. mirabilis as Gram-negative bacteria, A. niger and C. albicans fungi.


Assuntos
COVID-19/prevenção & controle , Celulose/química , Coronavirus/efeitos dos fármacos , Desinfetantes/química , Nanopartículas Metálicas/química , SARS-CoV-2/efeitos dos fármacos , Prata/química , Resinas Acrílicas/química , Antibacterianos/química , Anti-Infecciosos/química , Antivirais/química , Citratos/química , Fibra de Algodão , Fungos/efeitos dos fármacos , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Química Verde , Testes de Sensibilidade Microbiana , Nitrato de Prata/química
15.
Environ Sci Technol ; 55(8): 5143-5151, 2021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33726495

RESUMO

Widely applied silver nanoparticles (AgNPs) can have potentially detrimental impacts on aquatic organisms. Unicellular algae as primary producers can interact with AgNPs and initiate their transfer along food chains. Herein, we demonstrate that AgNPs were internalized in a freshwater phytoplankton species Chlamydomonas reinhardtii, but the entrance pathways varied with their surface coatings. Citrate-coated AgNPs (Cit-AgNPs) were internalized mainly through the apical zone of the cell near the flagella, whereas the aggregation-induced emission fluorogen (AIEgen)-coated AgNPs (AIE-AgNPs) were internalized through endocytosis. The internalized AgNPs were dissolved intracellularly and the released Ag+ was distributed heterogeneously in the cytoplasm, in contrast to the directly accumulated Ag+ which displayed a diffuse cytoplasmic distribution pattern. We then further visualized and quantified the trophic transfer of AgNPs from the alga C. reinhardtii to the zooplanktonic species Daphnia magna. Both trophically transferred Ag+ and AgNPs were concentrated in the gut regions of D. magna as a result of the direct ingestion of food particles. After ingestion, about 95% of the trophically transferred Ag+ was eliminated. Retention of AIE-AgNPs by daphnids was relatively higher than that of Cit-AgNPs due to their lower dissolution of Ag+. The present study provides direct evidence for the internalization of AgNPs in unicellular algae and demonstrates that the biological transport of trophically transferred of AgNPs is related to the different surface coatings of NPs.


Assuntos
Nanopartículas Metálicas , Poluentes Químicos da Água , Animais , Transporte Biológico , Daphnia , Prata , Nitrato de Prata
16.
Sci Total Environ ; 777: 146071, 2021 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-33684768

RESUMO

Silver nanoparticles (AgNPs) may reach the soil compartment via sewage sludge or nanoagrochemical applications. Understanding how NPs interact with biological systems is crucial for an accurate hazard assessment. Therefore, this study aimed at determining the Ag toxicokinetics in the mealworm Tenebrio molitor, exposed via Lufa 2.2 soil or via food to different Ag forms (uncoated 50 nm AgNPs, paraffin coated 3-8 nm and PVP-stabilised 60 nm, Ag2S NPs 20 nm, and ionic Ag). Mealworms were exposed for 21 days followed by a 21-day elimination phase (clean soil/food). A one-compartment kinetics model with inert fraction (simulating a storage compartment, where detoxified forms are located) was used to describe Ag accumulation. Fully understanding the uptake route in mealworms is difficult. For that reason several approaches were used, showing that food, soil and pore water all are valid uptake routes, but with different importance. Silver taken up from soil pore water or from soil showed to be related to Ag dissolution in soil pore water. In general, the uptake and elimination rate constants were similar for 3-8 nm and 60 nm AgNPs and for AgNO3, but significantly different for the uncoated 50 nm AgNPs. Upon food exposure, uptake rate constants were similar for 50 nm AgNPs and AgNO3, while those for 60 nm and 3-8 nm AgNPs and for Ag2S NPs also grouped together. NP exposure in soil appeared more difficult to characterize, with different patterns obtained for the different NPs. But it was evident that upon soil or food exposure, particle characteristics highly affected Ag bioavailability and bioaccumulation. Although Ag2S NPs were taken up, their elimination was faster than for other Ag forms, showing the lowest inert fraction. The significantly different elimination rate constants suggest that the mechanism of elimination may not be the same for different AgNPs either.


Assuntos
Nanopartículas Metálicas , Tenebrio , Animais , Nanopartículas Metálicas/toxicidade , Prata/toxicidade , Nitrato de Prata , Solo , Toxicocinética
17.
Rinsho Ketsueki ; 62(1): 35-41, 2021.
Artigo em Japonês | MEDLINE | ID: mdl-33551423

RESUMO

A 72-year-old man with leukocytosis, anemia, and lymphadenopathy was diagnosed with chronic lymphocytic leukemia (CLL) in August 2017 and was carefully monitored in a "watch-and-wait" manner until it became an "active disease." Ibrutinib (IBR) was initiated orally in July 2018 at a dose of 420 mg/day after disease progression due to chromosome 17p deletion (del 17p). The patient showed partial response after transient lymphocytosis while on IBR treatment. IBR induces paronychia and skin disorder due to the disruption of disulfide bonds between cysteine and inhibition of epidermal growth factor receptor due to the off-target effect. This results in reduced quality of life. In February 2019, paronychia (grade 1) developed in the patient's right foot's first toe; hence, topical gentamicin and taping therapy were performed. However, the symptoms persisted without any improvements. In July 2019, paronychia/granulation (grade 2) was aggravated and successfully treated with silver nitrate chemical cauterization and taping therapy. The patient was continuously treated with 420 mg/day IBR without dose reduction or discontinuation, resulting in successful disease control of CLL with del 17p.


Assuntos
Adenina/análogos & derivados , Leucemia Linfocítica Crônica de Células B , Paroniquia , Piperidinas/uso terapêutico , Adenina/uso terapêutico , Idoso , Cauterização , Humanos , Leucemia Linfocítica Crônica de Células B/tratamento farmacológico , Masculino , Inibidores de Proteínas Quinases , Qualidade de Vida , Nitrato de Prata
18.
ChemistryOpen ; 10(1): 28-45, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33448132

RESUMO

The conversion of the 1 : 1-complex of Cisplatin with 1-methyluracil (1MeUH), cis-[Pt(NH3 )2 (1MeU-N3)Cl] (1 a) to the aqua species cis-[Pt(NH3 )2 (1MeU-N3)(OH2 )]+ (1 b), achieved by reaction of 1 a with AgNO3 in water, affords a mixture of compounds, the composition of which strongly depends on sample history. The complexity stems from variations in condensation patterns and partial loss of NH3 ligands. In dilute aqueous solution, 1 a, and dinuclear compounds cis-[(NH3 )2 (1MeU-N3)Pt(µ-OH)Pt(1MeU-N3)(NH3 )2 ]+ (3) as well as head-tail cis-[Pt2 (NH3 )4 (µ-1MeU-N3,O4)2 ]2+ (4) represent the major components. In addition, there are numerous other species present in minor quantities, which differ in metal nuclearity, stoichiometry, stereoisomerism, and Pt oxidation state, as revealed by a combination of 1 H NMR and ESI-MS spectroscopy. Their composition appears not to be the consequence of a unique and repeating coordination pattern of the 1MeU ligand in oligomers but rather the coexistence of distinctly different condensation patterns, which include µ-OH, µ-1MeU, and µ-NH2 bridging and combinations thereof. Consequently, the products obtained should, in total, be defined as a heterogeneous mixture rather than a mixture of oligomers of different sizes. In addition, a N2 complex, [Pt(NH3 )(1MeU)(N2 )]+ appears to be formed in gas phase during the ESI-MS experiment. In the presence of Na+ ions, multimers n of 1 a with n=2, 3, 4 are formed that represent analogues of non-metalated uracil quartets found in tetrastranded RNA.


Assuntos
Complexos de Coordenação/química , Uracila/análogos & derivados , Amônia/química , Cisplatino/química , Complexos de Coordenação/síntese química , Ligantes , Estrutura Molecular , Nitrato de Prata/química , Uracila/síntese química , Uracila/química , Água/química
19.
Thorax ; 76(6): 632-633, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33514669

RESUMO

We present the cases of two laryngectomised patients who were treated for granulomas of the tracheostomy orifice with a silver nitrate pencil. During tracheostomy care, the tip broke off, was aspirated and fell into the bronchial tree. Necrotising ulcerative injuries of the right bronchial tree with clear delineation were found without lesions in the subsegmental division. To prevent the risk of secondary stenosis of the small airways induced by the spread of silver nitrate, we did not irrigate with saline solution as previously reported. Antibiotherapy and endoscopic monitoring were performed. Complete healing in 4-6 weeks was found without stenosis of the bronchial tree or bleeding.


Assuntos
Brônquios/diagnóstico por imagem , Corpos Estranhos/cirurgia , Nitrato de Prata/efeitos adversos , Traqueostomia/efeitos adversos , Idoso , Broncoscopia , Feminino , Corpos Estranhos/diagnóstico , Humanos , Inalação , Masculino , Pessoa de Meia-Idade
20.
Ecotoxicol Environ Saf ; 211: 111930, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33472113

RESUMO

Emerging research in mammalian cells suggests that ionic (AgNO3) and nano silver (AgNP) can disrupt the metabolism of selenium which plays a vital role in oxidative stress control. However, the effect of silver (Ag) on selenoprotein function in fish is poorly understood. Here we evaluate the effects of AgNO3 and citrate coated AgNP (cit-AgNP) on selenoprotein function and oxidative stress using a fish cell line derived from the rainbow trout (Oncorhynchus mykiss) intestine (RTgutGC). Cell viability was evaluated using a cytotoxicity assay which measures simultaneously metabolic activity, membrane integrity and lysosome integrity. Cells exposed to equimolar amounts of AgNO3 and cit-AgNP accumulated the same amount of silver intracellularly, however AgNO3 was more toxic than cit-AgNP. Selenoenzymes glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) mRNA levels and enzyme activity were measured. While mRNA levels remained unaffected by AgNO3 or cit-AgNP, the enzyme activity of GPx was inhibited by AgNO3 (1 µM) and cit-AgNP (5 µM) and TrxR activity was inhibited by AgNO3 (0.4 µM) and cit-AgNP (1, 5 µM). Moreover, cells exposed to 1 µM of AgNO3 and cit-AgNP showed an increase in metallothionein b (MTb) mRNA levels at 24 h of exposure, confirming the uptake of silver, but returned to control levels at 72 h suggesting silver scavenging by MTb. Oxidative stress was not observed at any of the doses of AgNO3 or cit-AgNP tested. Overall, this study shows that AgNO3 or cit-AgNP can inhibit the activity of selenoenzymes but do not induce oxidative stress in RTgutGC cells.


Assuntos
Nanopartículas Metálicas/toxicidade , Selenoproteínas/metabolismo , Prata/toxicidade , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Citratos , Ácido Cítrico , Glutationa Peroxidase/metabolismo , Intestinos , Íons/metabolismo , Metalotioneína/metabolismo , Oncorhynchus mykiss/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Selênio , Nitrato de Prata/toxicidade
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