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1.
Molecules ; 26(16)2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34443480

RESUMO

Within this study, new materials were synthesized and characterized based on polysiloxane modified with different ratios of N-acetyl-l-cysteine (NAC) and crosslinked via UV-assisted thiol-ene addition, in order to obtain efficient membranes able to resist bacterial adherence and biofilm formation. These membranes were subjected to in vitro testing for microbial adherence against S. pneumoniae using standardized tests. WISTAR rats were implanted for 4 weeks with crosslinked siloxane samples without and with NAC. A set of physical characterization methods was employed to assess the chemical structure and morphological aspects of the new synthetized materials before and after contact with the microbiological medium.


Assuntos
Antibacterianos/química , Materiais Revestidos Biocompatíveis/química , Implantes Cocleares/microbiologia , Otite/tratamento farmacológico , Polímeros/química , Siloxanas/química , Acetilcisteína/química , Acetilcisteína/farmacologia , Acetilcisteína/uso terapêutico , Animais , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Aderência Bacteriana/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/farmacologia , Materiais Revestidos Biocompatíveis/uso terapêutico , Implantes Cocleares/efeitos adversos , Polímeros/farmacologia , Polímeros/uso terapêutico , Ratos Wistar , Siloxanas/farmacologia , Siloxanas/uso terapêutico , Streptococcus pneumoniae/efeitos dos fármacos , Compostos de Sulfidrila/química , Propriedades de Superfície
2.
ACS Appl Mater Interfaces ; 13(27): 31355-31370, 2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34218662

RESUMO

The development of cancer resistance continues to represent a bottleneck of cancer therapy. It is one of the leading factors preventing drugs to exhibit their full therapeutic potential. Consequently, it reduces the efficacy of anticancer therapy and causes the survival rate of therapy-resistant patients to be far from satisfactory. Here, an emerging strategy for overcoming drug resistance is proposed employing a novel two-dimensional (2D) nanomaterial polysiloxane (PSX). We have reported on the synthesis of PSX nanosheets (PSX NSs) and proved that they have favorable properties for biomedical applications. PSX NSs evinced unprecedented cytocompatibility up to the concentration of 300 µg/mL, while inducing very low level of red blood cell hemolysis and were found to be highly effective for anticancer drug binding. PSX NSs enhanced the efficacy of the anticancer drug doxorubicin (DOX) by around 27.8-43.4% on average and, interestingly, were found to be especially effective in the therapy of drug-resistant tumors, improving the effectiveness of up to 52%. Fluorescence microscopy revealed improved retention of DOX within the drug-resistant cells when bound on PSX NSs. DOX bound on the surface of PSX NSs, i.e., PSX@DOX, improved, in general, the DOX cytotoxicity in vitro. More importantly, PSX@DOX reduced the growth of DOX-resistant tumors in vivo with 3.5 times better average efficiency than the free drug. Altogether, this paper represents an introduction of a new 2D nanomaterial derived from silicane and pioneers its biomedical application. As advances in the field of material synthesis are rapidly progressing, novel 2D nanomaterials with improved properties are being synthesized and await thorough exploration. Our findings further provide a better understanding of the mechanisms involved in the cancer resistance and can promote the development of a precise cancer therapy.


Assuntos
Doxorrubicina/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Neoplasias Ovarianas/tratamento farmacológico , Siloxanas/farmacologia , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Modelos Animais de Doenças , Doxorrubicina/uso terapêutico , Feminino , Humanos , Teste de Materiais , Camundongos , Nanoestruturas/química , Siloxanas/química
3.
Chem Biol Interact ; 345: 109564, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34161785

RESUMO

Suppressive effect of bis (3-amino-2-pyridine) diselenide (BAPD) on psychiatric disorders - atopic dermatitis (AD) comorbidity in mice was investigated. To sensitize the animals, 2,4-dinitrochlorobenzene (DNCB) was applied to their dorsal skin on days 1-3. Mice were challenged with DNCB on their ears and dorsal skin on days 14, 17, 20, 23, 26, and 29. BAPD and Dexamethasone were administered to the animals, from days 14-29, and skin severity scores and behavioral tests were determined. Oxidative stress and inflammatory parameters were evaluated on the dorsal skin of mice. Na+, K+-ATPase activity and corticosterone levels were determined in hippocampus/cerebral cortex and plasma of mice, respectively. BAPD improved cutaneous damage, scratching behavior, inflammatory and oxidative stress markers. BAPD showed anxiolytic- and antidepressant-like effects and restored Na+, K+-ATPase activity and corticosterone levels. The present study was performed using female mice due the susceptibility for this disease. But, the evaluation of AD model in male mice would help to verify whether the male gender has the same predisposition to present this pathology. Our data demonstrated the suppressive effect of BAPD on psychiatric disorders - AD comorbidity by regulating inflammatory and oxidative status in mice.


Assuntos
Dermatite Atópica/tratamento farmacológico , Dermatite Atópica/epidemiologia , Transtornos Mentais/tratamento farmacológico , Transtornos Mentais/epidemiologia , Siloxanas/farmacologia , Animais , Comportamento Animal/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Comorbidade , Corticosterona/sangue , Corticosterona/metabolismo , Dermatite Atópica/complicações , Dermatite Atópica/metabolismo , Feminino , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Inflamação/complicações , Transtornos Mentais/complicações , Transtornos Mentais/metabolismo , Camundongos , Oxirredução/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Siloxanas/uso terapêutico
4.
Molecules ; 26(4)2021 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-33557279

RESUMO

Intrinsic hydrophobicity is the reason for efficient bacterial settlement and biofilm growth on silicone materials. Those unwelcomed phenomena may play an important role in pathogen transmission. We have proposed an approach towards the development of new anti-biofilm strategies that resulted in novel antimicrobial hydrophobic silicones. Those functionalized polysiloxanes grafted with side 2-(carboxymethylthioethyl)-, 2-(n-propylamidomethylthioethyl)- and 2-(mercaptoethylamidomethylthioethyl)- groups showed a wide range of antimicrobial properties towards selected strains of bacteria (reference strains Staphylococcus aureus, Escherichia coli and water-borne isolates Agrobacterium tumefaciens, Aeromonas hydrophila), fungi (Aureobasidium pullulans) and algae (Chlorella vulgaris), which makes them valuable antibacterial and antibiofilm agents. Tested microorganisms showed various levels of biofilm formation, but particularly effective antibiofilm activity was demonstrated for bacterial isolate A. hydrophila with high adhesion abilities. In the case of modified surfaces, the relative coefficient of adhesion for this strain was 18 times lower in comparison to the control glass sample.


Assuntos
Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Adesão Celular/efeitos dos fármacos , Interações Hidrofóbicas e Hidrofílicas , Siloxanas/química , Siloxanas/farmacologia , Anti-Infecciosos/síntese química , Siloxanas/síntese química
5.
Molecules ; 25(7)2020 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-32260260

RESUMO

Multidrug resistance (MDR) that occurs in cancer cells constitutes one of the major reasons for chemotherapy failure. The main molecular mechanism of MDR is overexpression of protein transporters from the ATP-binding cassette (ABC) superfamily, such as ABCB1 (multidrug resistance protein 1 (MDR1), P-glycoprotein). At the expense of ATP hydrolysis, ABCB1 pumps a diverse range of substrates (including anticancer drugs) out of the cell, thereby reducing their intracellular concentration. In the present study, the ability of two patented disiloxanes (SILA-409 and SILA-421) to reverse drug resistance in human colon adenocarcinoma cell lines LoVo and LoVo/Dx was investigated. It was demonstrated that both compounds in concentrations of 0.5-1 µM strongly increased the sensitivity of LoVo/Dx cells to doxorubicin. By means of an accumulation test in which rhodamine 123 was used as an ABCB1 substrate analogue, both organosilicon compounds were also shown to inhibit ABCB1 transport activity. The intracellular accumulation of doxorubicin was also increased, and more drug entered the cellular nuclei of resistant cells in the presence of the studied compounds. In conclusion, both SILA-409 and SILA-421 were demonstrated to be effective MDR reversal agents in resistant human colon cancer cells.


Assuntos
Neoplasias do Colo/metabolismo , Doxorrubicina/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Piperazinas/farmacologia , Siloxanas/farmacologia , Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Neoplasias do Colo/tratamento farmacológico , Sinergismo Farmacológico , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos
6.
Poult Sci ; 99(3): 1581-1590, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32111324

RESUMO

The spatial network structure of Dergall is based on substances nontoxic to humans and the environment which, when applied on solid surfaces, creates a coating that reduces bacterial cell adhesion. The bacteriostatic properties of siloxanes are based on a purely physical action mechanism which excludes development of drug-resistant microorganisms. The aims of the present study were to 1) evaluate a Dergall layer formed on the eggshell surface regarding the potential harmful effects on the chick embryo; 2) evaluate antimicrobial activity and estimate the prolongation time of Dergall's potential antimicrobial activity. Dergall at a concentration of 0.6% formed a layer on the eggshell surface. In vitro testing of the potential harmful effects of Dergall by means of a hen embryo test of the chorioallantoic membrane showed no irritation reaction at a concentration of 3% and lower. The hatchability of the groups sprayed with a Dergall water solution with a concentration of 0 to 5% was 89.1 to 93.8% for fertilized eggs (P > 0.05) but decreased to 63.7% (P < 0.05) in the group sprayed with a 6% concentration of the solution. This phenomenon was caused by embryo mortality in the first week of incubation. At the concentration of 0.6%, Dergall exhibited strong antibacterial properties against bacteria such as Staphylococcus aureus, Escherichia coli, Shigella dysenteriae, Shigella flexneri, and Salmonella typhimurium. For Streptococcus pyogenes, the highest antibacterial activity of Dergall was reported in the concentrations of 100 and 50%. For Pseudomonas aeruginosa, no antibacterial activity of Dergall was generally observed, but in vivo testing showed a strong decrease of all gram-negative bacteria growth. Moreover, a prolonged antimicrobial effect lasting until 3 D after disinfection was observed, which makes Dergall a safe and efficient disinfectant.


Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Embrião de Galinha/efeitos dos fármacos , Casca de Ovo/efeitos dos fármacos , Siloxanas/farmacologia , Animais , Antibacterianos/administração & dosagem , Antibacterianos/química , Bactérias/crescimento & desenvolvimento , Fenômenos Fisiológicos Bacterianos/efeitos dos fármacos , Embrião de Galinha/crescimento & desenvolvimento , Galinhas , Relação Dose-Resposta a Droga , Casca de Ovo/microbiologia , Siloxanas/administração & dosagem , Siloxanas/química
7.
Biomacromolecules ; 20(11): 4230-4240, 2019 11 11.
Artigo em Inglês | MEDLINE | ID: mdl-31633916

RESUMO

Hyperbranched polysiloxane (HBPSi) is attracting increasing attention due to its intrinsic fluorescence and good biocompatibility. However, it is very challenging to explore its biological applications because of the low fluorescence intensity and quantum yield. Herein, we introduced rigid ß-cyclodextrin to the end of flexible polysiloxane chain to synthesize a novel fluorescent polymer (HBPSi-CD) and explore its biological applications. Results showed that the fluorescence intensity and quantum yield of HBPSi-CD, compared with HBPSi, were significantly enhanced. Theoretical calculations and transmission electron microscopy demonstrated that the synergy effect of intra/intermolecular hydrogen bonds and hydrophobic effect promoted the formation of large supramolecular self-assemblies and space electron delocalization systems, leading to intense fluorescence. Notably, the biocompatible HBPSi-CD not only lighted up mouse fibroblast cells, but also possessed high ibuprofen loading capacity (160 mg g-1) and superior pH-responsive drug release performance. This work promoted the development of biological applications of HBPSi.


Assuntos
Sistemas de Liberação de Medicamentos , Imagem Molecular/métodos , Siloxanas/química , beta-Ciclodextrinas/química , Animais , Materiais Biocompatíveis/química , Rastreamento de Células/métodos , Corantes Fluorescentes/química , Corantes Fluorescentes/farmacologia , Humanos , Ligação de Hidrogênio/efeitos dos fármacos , Camundongos , Siloxanas/farmacologia , beta-Ciclodextrinas/farmacologia
9.
Vet Parasitol ; 269: 53-56, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31079828

RESUMO

Infestations of Rhipicephalus microplus cause significant damage to cattle breeding and their control is primarily based on chemical products. There are extensive reports of efficacy losses of acaricid products over time, as well as resistance of the parasites to them, thereby making it necessary to search for new alternatives. The present work aimed to determine the in vitro and in vivo acaricidal activity of organo-modified siloxanes with and without piperonyl butoxide (PBO) in southern Brazil. For the in vitro test, engorged females of R. microplus were collected and submitted to the immersion test. The formulation containing organo-modified siloxanes was tested at 4 different concentrations: 0.6, 1.0, 2.5, and 5.0%. The lowest dilutions (0.6, 1.0, and 2.5%) were also tested with the inclusion of 10% PBO. The in vivo test was performed by applying 2.5% organo-modified siloxanes, and the addition of 10% PBO was applied by spraying. The results showed high acaricidal activity (100%) in vitro in the concentration of 5% on non-associated forms, and in combinations of concentrations of 0.6, 1.0, 2.5% with PBO. The in vivo results also increased the efficacy with the association of PBO. In view of the current multi-resistance scenario of the R. microplus tick to the different commercially available acaricidal products, this study investigated the use of this product in association with PBO as an alternative to R. microplus control and found positive results. To the authors' knowledge, this is the first study to use organo-modified siloxanes against ticks.


Assuntos
Acaricidas/farmacologia , Doenças dos Bovinos/parasitologia , Butóxido de Piperonila/farmacologia , Rhipicephalus/efeitos dos fármacos , Siloxanas/farmacologia , Infestações por Carrapato/veterinária , Acaricidas/química , Animais , Bovinos , Resistência a Medicamentos , Feminino , Siloxanas/química , Infestações por Carrapato/parasitologia
10.
Carbohydr Polym ; 217: 15-25, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31079671

RESUMO

A bifunctional interfacial layer was introduced onto the surface of cotton fabric which not only enhanced the interfacial bonding between Ag@ZnO and organic substrates but also improved the photocatalytic performance simultaneously. In detail, a modified cotton fabric (denoted as Cot-g-Si/Ag@ZnO) was fabricated through radiation-induced graft polymerization of γ-methacryloxypropyl trimethoxysilane and followed the in-situ formation of ZnO and loading of Ag nanoparticles simultaneously. Owing to ZnOSi between the graft chains and Ag@ZnO photocatalyst, the charge carrier concentration increased and Ag was prevented from oxidizing through the partial separation from ZnO, leading to enhanced near-field amplitudes of the localized surface plasmon resonance. Cot-g-Si/Ag@ZnO also exhibited excellent photocorrosion resistance, photostability and laundering durability. Its photocatalytic activity was fully maintained after several photodegradation cycles; moreover, after laundering durability test, the photocatalytic activity was improved compared with the newly prepared one. Credible mechanism for the photocatalytic activity of Cot-g-Si/Ag@ZnO under sunlight irradiation is proposed.


Assuntos
Antibacterianos/farmacologia , Fibra de Algodão , Nanopartículas Metálicas/química , Siloxanas/farmacologia , Prata/química , Óxido de Zinco/farmacologia , Antibacterianos/química , Antibacterianos/efeitos da radiação , Catálise , Escherichia coli/efeitos dos fármacos , Gossypium/química , Luz , Nanopartículas Metálicas/efeitos da radiação , Azul de Metileno/efeitos da radiação , Fotólise , Rodaminas/efeitos da radiação , Siloxanas/química , Siloxanas/efeitos da radiação , Prata/efeitos da radiação , Staphylococcus aureus/efeitos dos fármacos , Óxido de Zinco/química , Óxido de Zinco/efeitos da radiação
11.
Int J Mol Sci ; 20(8)2019 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-31022884

RESUMO

Antibiofilm strategies may be based on the prevention of initial bacterial adhesion, the inhibition of biofilm maturation or biofilm eradication. N-acetyl-L-cysteine (NAC), widely used in medical treatments, offers an interesting approach to biofilm destruction. However, many Eubacteria strains are able to enzymatically decompose the NAC molecule. This is the first report on the action of two hybrid materials, NAC-Si-1 and NAC-Si-2, against bacteria isolated from a water environment: Agrobacterium tumefaciens, Aeromonas hydrophila, Citrobacter freundii, Enterobacter soli, Janthinobacterium lividum and Stenotrophomonas maltophilia. The NAC was grafted onto functional siloxane polymers to reduce its availability to bacterial enzymes. The results confirm the bioactivity of NAC. However, the final effect of its action was environment- and strain-dependent. Moreover, all the tested bacterial strains showed the ability to degrade NAC by various metabolic routes. The NAC polymers were less effective bacterial inhibitors than NAC, but more effective at eradicating mature bacterial biofilms.


Assuntos
Acetilcisteína/farmacologia , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Água Potável/microbiologia , Siloxanas/farmacologia , Acetilcisteína/química , Antibacterianos/química , Aderência Bacteriana/efeitos dos fármacos , Siloxanas/química , Purificação da Água
12.
Colloids Surf B Biointerfaces ; 175: 596-605, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30580150

RESUMO

Biomaterials are frequently evaluated for pro-coagulant activity but usually in the presence of microparticles (MPs), cell-derived vesicles in blood plasma whose phospholipid surfaces allow coagulation factors to set up as functional assemblies. We tested the hypothesis that synthetic anionic surfaces can catalyze burst thrombin activation in human blood plasma in the absence of MPs. In a thromboelastography (TEG) assay with plastic sample cups and pins, recalcified human citrated platelet-poor plasma spontaneously burst-coagulated but with an unpredictable clotting time whereas plasma depleted of MPs by ultracentrifugation failed to coagulate. Coagulation of MP-depleted plasma was restored in a dose-dependent manner by glass microbeads, hydroxyapatite nanoparticles (HA NPs), and carboxylic acid-containing anionic nanocoatings of TEG cups and pins (coated by glow-discharge plasma-polymerized ethylene containing oxygen, L-PPE:O with 4.4 and 6.8 atomic % [COOH]). Glass beads lost their pro-coagulant activity in MP-depleted plasma after their surfaces were nanocoated with hydrophobic plasma-polymerized hexamethyl disiloxane (PP-HMDSO). In FXII-depleted MP-depleted plasma, glass microbeads failed to induce coagulation, however, FXIa was sufficient to induce coagulation in a dose-dependent manner, with no effect of glass beads. These data suggest that anionic surfaces of crystalline, organic, and amorphous solid synthetic materials catalyze explosive thrombin generation in MP-depleted plasma by activating the FXII-dependent intrinsic contact pathway. The data also show that microparticles are pro-coagulant surfaces whose activity has been largely overlooked in many coagulation studies to-date. These results suggest a possible mechanism by which anionic biomaterial surfaces induce bone healing by contact osteogenesis, through fibrin clot formation in the absence of platelet activation.


Assuntos
Materiais Biocompatíveis/farmacologia , Coagulação Sanguínea/efeitos dos fármacos , Micropartículas Derivadas de Células/química , Durapatita/farmacologia , Nanopartículas/química , Siloxanas/farmacologia , Ânions , Materiais Biocompatíveis/química , Plaquetas/citologia , Plaquetas/efeitos dos fármacos , Durapatita/química , Fator XII/metabolismo , Vidro/química , Humanos , Membranas Artificiais , Siloxanas/química , Propriedades de Superfície , Tromboelastografia , Trombina/metabolismo
13.
Mater Sci Eng C Mater Biol Appl ; 93: 380-389, 2018 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-30274070

RESUMO

Long-term live cell tracking is desirable and necessary to understand the dynamics and complexity of biological interactions in stem cells and cancer cells. Conventional live cells fluorescence trackers are generally non-degradable and are showing increased toxicity concerns during the long-term application. Previously we developed biodegradable fluorescent poly(citrate)-based hybrid elastomers for bone regeneration applications. Here, we fabricated the photoluminescent poly(citrate-siloxane) nanoparticles (PCSNPs) through an oil/water emulsion method and demonstrated their long-term live stem cells/cancer cells imaging applications. PCSNPs showed a uniform size distribution (mean diameter 120 nm) and highly stable dispersability (above 30 days) in various physiological medium, as well as excellent fluorescent properties and photostability. PCSNPs possess excellent cellular biocompatibility, which could be efficiently internalized by cells and selectively image the cell lysosome with a high photostability. Compared with commercial Cell Tracker™ Green and Cell Tracker™ Red, the adipose-derived mesenchymal stem cells or human hepatoma cells were stably labeled by PCSNPs for over 14 days as they grew and developed (7 passages). Additionally, PCSNPs efficiently tracked cells up to 7 days in vivo through a non-invasively way compared with 1 day of commercial tracker. This study demonstrates an important strategy to design biodegradable multifunctional delivery platforms for biomedical applications such as long-term bioimaging.


Assuntos
Rastreamento de Células/métodos , Elastômeros , Medições Luminescentes/métodos , Teste de Materiais , Células-Tronco Mesenquimais/citologia , Siloxanas , Elastômeros/química , Elastômeros/farmacologia , Células Hep G2 , Humanos , Células-Tronco Mesenquimais/metabolismo , Nanopartículas/química , Siloxanas/química , Siloxanas/farmacologia
14.
J Colloid Interface Sci ; 526: 43-50, 2018 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-29715614

RESUMO

Magnesium (Mg) alloys have shown great potential in biomedical materials due to their biocompatibility and biodegradability. However, rapid corrosion rate, which is an inevitable obstacle, hinders their clinical applications. Besides, it is necessary to endow Mg alloys with antibacterial properties, which are crucial for temporary implants. In this study, silver nanoparticles (AgNPs) and polymethyltrimethoxysilane (PMTMS) were introduced into AZ31 Mg alloys via layer-by-layer (LbL) assembly and siloxane self-condensation reaction. The characteristics of the composite films were investigated by SEM, UV-vis, FT-IR, and XRD measurements. Corrosion resistance of the samples was measured by electrochemical and hydrogen evolution tests. Antibacterial activities of the films against Staphylococcus aureus were evaluated by plate-counting method. The results demonstrated that the composite film with smooth and uniform morphologies could enhance the corrosion resistance of Mg alloys owing to the physical barrier and the self-healing functionality of polysiloxane. Moreover, the composite coating possessed antibacterial properties and could prolong the release of assembled silver ions.


Assuntos
Ligas , Antibacterianos , Magnésio , Siloxanas , Staphylococcus aureus/crescimento & desenvolvimento , Ligas/química , Ligas/farmacologia , Antibacterianos/química , Antibacterianos/farmacologia , Corrosão , Magnésio/química , Magnésio/farmacologia , Nanopartículas Metálicas/química , Polivinil/química , Polivinil/farmacologia , Siloxanas/química , Siloxanas/farmacologia , Prata/química , Prata/farmacologia
15.
Arch Toxicol ; 92(5): 1685-1702, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29632997

RESUMO

The European Commission has recently proposed draft criteria for the identification of endocrine disrupting chemicals (EDCs) that pose a significant hazard to humans or the environment. Identifying and characterizing toxic hazards based on the manner by which adverse effects are produced rather than on the nature of those adverse effects departs from traditional practice and requires a proper interpretation of the evidence regarding the chemical's ability to produce physiological effect(s) via a specific mode of action (MoA). The ability of any chemical to produce a physiological effect depends on its pharmacokinetics and the potency by which it acts via the various MoAs that can lead to the particular effect. A chemical's potency for a specific MoA-its mechanistic potency-is determined by two properties: (1) its affinity for the functional components that comprise the MoA, i.e., its specific receptors, enzymes, transporters, transcriptional elements, etc., and (2) its ability to alter the functional state of those components (activity). Using the agonist MoA via estrogen receptor alpha, we illustrate an empirical method for determining a human-relevant potency threshold (HRPT), defined as the minimum level of mechanistic potency necessary for a chemical to be able to act via a particular MoA in humans. One important use for an HRPT is to distinguish between chemicals that may be capable of, versus those likely to be incapable of, producing adverse effects in humans via the specified MoA. The method involves comparing chemicals that have different ERα agonist potencies with the ability of those chemicals to produce ERα-mediated agonist responses in human clinical trials. Based on this approach, we propose an HRPT for ERα agonism of 1E-04 relative to the potency of the endogenous estrogenic hormone 17ß-estradiol or the pharmaceutical estrogen, 17α-ethinylestradiol. This approach provides a practical way to address Hazard Identification according to the draft criteria for identification of EDCs recently proposed by the European Commission.


Assuntos
Receptor alfa de Estrogênio/agonistas , Estrogênios/metabolismo , Testes de Toxicidade/métodos , Adolescente , Criança , Disruptores Endócrinos/farmacologia , Disruptores Endócrinos/toxicidade , Determinação de Ponto Final , Estradiol/farmacologia , Estrogênios/farmacologia , Etinilestradiol/farmacologia , Feminino , Humanos , Ciclo Menstrual/fisiologia , Puberdade , Siloxanas/farmacologia
16.
Parasite ; 25: 8, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29521258

RESUMO

Chemical, physical, and mechanical methods are used to control human lice. Attempts have been made to eradicate head lice Pediculus humanus capitis by hot air, soaking in various fluids or asphyxiation using occlusive treatments. In this study, we assessed the maximum time that head lice can survive anoxia (oxygen deprivation) and their ability to survive prolonged water immersion. We also observed the ingress of fluids across louse tracheae and spiracle characteristics contrasting with those described in the literature. We showed that 100% of lice can withstand 8 h of anoxia and 12.2% survived 14 h of anoxia; survival was 48.9% in the untreated control group at 14 h. However, all lice had died following 16 h of anoxia. In contrast, the survival rate of water-immersed lice was significantly higher when compared with non-immersed lice after 6 h (100% vs. 76.6%, p = 0.0037), and 24 h (50.9% vs. 15.9%, p = 0.0003). Although water-immersed lice did not close their spiracles, water did not penetrate into the respiratory system. In contrast, immersion in colored dimeticone/cyclomethicone or colored ethanol resulted in penetration through the spiracles and spreading to the entire respiratory system within 30 min, leading to death in 100% of the lice.


Assuntos
Infestações por Piolhos/terapia , Oxigênio/fisiologia , Pediculus/efeitos dos fármacos , Pediculus/fisiologia , Água/farmacologia , Adolescente , Adulto , Idoso , Animais , Bioensaio , Criança , Pré-Escolar , Dimetilpolisiloxanos/farmacologia , Etanol/farmacologia , Humanos , Infestações por Piolhos/parasitologia , Pessoa de Meia-Idade , Siloxanas/farmacologia , Adulto Jovem
17.
Colloids Surf B Biointerfaces ; 164: 144-154, 2018 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-29413591

RESUMO

Medical device-related infections represent a major healthcare complication, resulting in potential risks for the patient. Antimicrobial materials comprise an attractive strategy against bacterial colonization and biofilm proliferation. However, in most cases these materials are only bacteriostatic or bactericidal, and consequently they must be used in combination with other antimicrobials in order to reach the eradication condition (no viable microorganisms). In this study, a straightforward and robust antibacterial coating based on Phosphotungstate Ormosil doped with core-shell (SiO2@TiO2) was developed using sol-gel process, chemical tempering, and Ag nanoparticle photoassisted synthesis (POrs-CS-Ag). The coating was characterized by X-ray Fluorescence Spectroscopy (XRF), Field Emission Scanning Electron Microscopy (FE-SEM), Atomic Force Microscopy (AFM) and X-ray Photoelectron Microscopy (XPS). The silver free coating displays low antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, in opposition to the silver loaded ones, which are able to completely eradicate these strains. Moreover, the antimicrobial activity of these substrates remains high until three reutilization cycles, which make them a promising strategy to develop self-sterilizing materials, such as POrs-CS-Ag-impregnated fabric, POrs-CS-Ag coated indwelling metals and polymers, among other materials.


Assuntos
Luz , Nanopartículas Metálicas/química , Siloxanas/farmacologia , Prata/química , Esterilização , Antibacterianos/farmacologia , Aderência Bacteriana/efeitos dos fármacos , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Microscopia de Força Atômica , Espectroscopia Fotoeletrônica , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Espectrofotometria Ultravioleta , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Propriedades de Superfície
18.
J Biomed Mater Res B Appl Biomater ; 106(3): 1138-1147, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-28544508

RESUMO

A series of sol-gel derived silicon based coatings were developed to improve the osseointegration of commercial titanium dental implants. The osseointegration starts with a positive interaction between the implant surface and surrounding tissues, which is facilitated by the adsorption of plasma proteins onto the biomaterial surface immediately after implantation. It is likely that the enhancement of protein adsorption to titanium implants leads to a better implant/tissue integration. In addition, silica based biomaterials have been shown to promote osteoblast differentiation. To improve the protein adsorption and the osteogenesis, methyltrimethoxysilane (MTMOS), tetraethoxysilane (TEOS), 3-glycidoxypropyltrimethoxysilane (GPTMS), and gelatin were selected to coat titanium surfaces. Compared with non-coated titanium, the functionalized coatings enhanced the adsorption of adhesive proteins such as fibronectin and collagen. The Si release was successfully modulated by the control of the chemical composition of the coating, showing a higher dissolution rate with the gelatin and GPTMS incorporation. While the roughness of commercial implants seemed to promote the adhesion of mesenchymal stem cells (MSC), the osteogenic differentiation was greater on surfaces with Si-coatings. In this study, an improved osteogenic surface has been achieved by using the siloxane-gelatin coatings and such coatings can be used in dental implants to promote osseointegration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1138-1147, 2018.


Assuntos
Proteínas Sanguíneas/química , Materiais Revestidos Biocompatíveis/farmacologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Siloxanas/farmacologia , Titânio/farmacologia , Adesão Celular , Células Cultivadas , Colágeno/química , Fibronectinas/química , Humanos , Osseointegração , Próteses e Implantes
19.
Implant Dent ; 26(6): 911-914, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29084027

RESUMO

AIM: The aim of this in vitro study was to assess the antimicrobial efficacy of materials (gutta percha [GP], polytetrafluoroethylene [PTFE] tape, and vinyl polysiloxane [VP]) used for sealing the implant abutment screw hole (IASH). METHODS: Sixty implants with a Morse cone connection were used. The implants were randomly divided into 3 groups (20 implants/group). In groups 1, 2, and 3, the IASH was sealed with GP, PTFE, and VP, respectively. Unstimulated whole saliva (UWS) was used as a contaminant medium for the incubation of the specimens. After 7 days of incubation, the specimens were opened under aseptic conditions, and the contents of the inner parts of the IASH were collected using sterile microbrushes. The occurrence of microbial leakage through the screw access channel interface was assessed with the checkerboard DNA-DNA hybridization method. P < 0.05 was considered statistically significant. RESULTS: Among samples in groups 1, 2, and 3, the UWS collected before incubation showed no statistically significant differences in relation to the prevalence of species investigated. Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Candida albicans were isolated from group 1 than groups 2 and 3. CONCLUSION: The choice of material for sealing the IASH is entirely dependent on the operators' choice and experience.


Assuntos
Antibacterianos/farmacologia , Dente Suporte , Implantes Dentários/microbiologia , Guta-Percha/farmacologia , Politetrafluoretileno/farmacologia , Polivinil/farmacologia , Siloxanas/farmacologia , Bactérias/isolamento & purificação , Parafusos Ósseos , Projeto do Implante Dentário-Pivô , Infiltração Dentária , Técnicas In Vitro , Teste de Materiais
20.
Dental Press J Orthod ; 22(4): 77-85, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28902253

RESUMO

Introduction:: Plasma-polymerized film deposition was created to modify metallic orthodontic brackets surface properties in order to inhibit bacterial adhesion. Methods:: Hexamethyldisiloxane (HMDSO) polymer films were deposited on conventional (n = 10) and self-ligating (n = 10) stainless steel orthodontic brackets using the Plasma-Enhanced Chemical Vapor Deposition (PECVD) radio frequency technique. The samples were divided into two groups according to the kind of bracket and two subgroups after surface treatment. Scanning Electron Microscopy (SEM) analysis was performed to assess the presence of bacterial adhesion over samples surfaces (slot and wings region) and film layer integrity. Surface roughness was assessed by Confocal Interferometry (CI) and surface wettability, by goniometry. For bacterial adhesion analysis, samples were exposed for 72 hours to a Streptococcus mutans solution for biofilm formation. The values obtained for surface roughness were analyzed using the Mann-Whitney test while biofilm adhesion were assessed by Kruskal-Wallis and SNK test. Results:: Significant statistical differences (p< 0.05) for surface roughness and bacterial adhesion reduction were observed on conventional brackets after surface treatment and between conventional and self-ligating brackets; no significant statistical differences were observed between self-ligating groups (p> 0.05). Conclusion: : Plasma-polymerized film deposition was only effective on reducing surface roughness and bacterial adhesion in conventional brackets. It was also noted that conventional brackets showed lower biofilm adhesion than self-ligating brackets despite the absence of film.


Assuntos
Aderência Bacteriana/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Braquetes Ortodônticos/microbiologia , Siloxanas/farmacologia , Streptococcus mutans/efeitos dos fármacos , Streptococcus mutans/fisiologia , Desenho de Aparelho Ortodôntico , Plasma , Polimerização , Streptococcus mutans/isolamento & purificação , Propriedades de Superfície
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