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2.
J Ethnopharmacol ; 246: 112188, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31470085

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Cymbopogon citratus (lemongrass) essential oil has been widely used as a traditional medicine and is well known for antimicrobial properties. Therefore, it might be a potent anti-infective and biofilm inhibitive against Candida tropicalis infections. Until now, no ideal coating or cleaning method based on an essential oil has been described to prevent biofilm formation of Candida strains on silicone rubber maxillofacial prostheses, voice prostheses and medical devices susceptible to C. tropicalis infections. AIM OF THE STUDY: To investigate the antifungal and biofilm inhibitory effects of Cymbopogon citratus oil. Clinical isolates of C. tropicalis biofilms on different biomaterials were used to study the inhibitory effect. MATERIALS AND METHODS: The efficacy of Cymbopogon citratus, Cuminum cyminum, Citrus limon and Cinnamomum verum essential oils were compared on biofilm formation of three C. tropicalis isolates on 24 well polystyrene plates. C. citratus oil coated silicone rubber surfaces were prepared using hypromellose ointment as a vehicle. The antifungal tests to determine minimum inhibitory and minimum fungicidal concentrations were assessed by a microbroth dilution method and biofilm formation was determined by a crystal violet binding assay. RESULTS: C. tropicalis strains formed more biofilm on hydrophobic materials than on hydrophilic glass. C. citratus oil showed a high antifungal effect against all C. tropicalis strains. For comparison, C. limon oil and C. cyminum oil showed minor to no killing effect against the C. tropicalis strains. C. citratus oil had the lowest minimal inhibitory concentration of all essential oils tested and inhibited biofilm formation of all C. tropicalis strains. C. citratus oil coating on silicone rubber resulted in a 45-76% reduction in biofilm formation of all C. tropicalis strains. CONCLUSION: Cymbopogon citratus oil has good potential to be used as an antifungal and antibiofilm agent on silicone rubber prostheses and medical devices on which C. tropicalis biofilms pose a serious risk for skin infections and may cause a shorter lifespan of the prosthesis.


Assuntos
Antifúngicos/farmacologia , Biofilmes/efeitos dos fármacos , Candida tropicalis/efeitos dos fármacos , Cymbopogon , Óleos Voláteis/farmacologia , Materiais Biocompatíveis , Candida tropicalis/fisiologia , Testes de Sensibilidade Microbiana , Próteses e Implantes/microbiologia , Elastômeros de Silicone
4.
Eur J Prosthodont Restor Dent ; 27(4): 172-181, 2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31769939

RESUMO

AIM: The colour stability of the silicone is essential for the longevity of facial prostheses. This in vitro study investigates the colour degradation of two different skin shade silicones moulded in Type II and Type III dental stone. METHODS & MATERIALS: Two different types of dental stone were used to fabricate 168 silicone samples (n=42 for each group) using M511 maxillofacial silicone, which was coloured with Spectromatch Procolourants. The polymerisation was carried out at 85°C 1.5 hours. A spectrophotometer was used to record the colour differences (ΔΕ) of each group before and after polymerisation. The CIEL*a*b* formula was used to obtain the measurements and a one-way ANOVA was carried out for the statistical analysis of the data. RESULTS: There is a statistically significant colour difference (ΔΕ) for all groups. For the Afro-Caribbean skin tone, Type III dental stone demonstrated the greatest colour change (ΔΕ = 4.36), whereas, for the Caucasian skin tone, it was the Type II dental stone (ΔΕ = 2.21). CONCLUSION: This study showed that regardless of the investing material, the colour of the silicone lightens after polymerisation. Both types of dental stone resulted in visible colour changes, with a ΔΕ ranging from 1.64 - 4.36.


Assuntos
Prótese Maxilofacial , Elastômeros de Silicone , Região do Caribe , Cor , Teste de Materiais , Pigmentação da Pele
5.
Vestn Oftalmol ; 135(5. Vyp. 2): 199-203, 2019.
Artigo em Russo | MEDLINE | ID: mdl-31691660

RESUMO

At present, installation of punctal plugs (tear duct occluders) draws attention of ophthalmologists, but this method of treating dry eye syndrome (DES) is not without complications. Considering the rise of DES occurrence - the tendency anticipated to continue - as well as expansion of indications for installation of tear duct occluders, their usage can be expected to rise. The article describes a relatively rare clinical case that involved intracanalicular migration of silicone punctal plug. A female patient of 36 years old sought medical help in Research Institute of Eye Diseases (Moscow) to treat a lump in the area of lower lacrimal punctum in the left eye that was growing in size; the lump had appeared around 2 months prior to the visit. Patient's medical history read that around 2 years ago she had a silicone occluder installed in the lower lacrimal punctum of the left eye. On examination, in the area of lower lacrimal punctum, a body with a nutrient vascular pedicle deriving from lower lacrimal duct could be found. The occluder was absent in the opening of the lacrimal punctum. A revision of lower tear duct cavity was performed to remove its contents. The body filling tear duct opening was removed with forceps. Substance was then sent for histological examination. Tear duct was scraped out, the silicone occluder removed and sent to laboratory for scanning electron microscopy. The patient had no complaints 6 months after the procedure. CONCLUSION: The study showed that the forming body was granuloma resulting from aseptic inflammation. Surface of the silicone occluder in retention of lacrimal pathways remained unchanged. Described surgical tactic is suitable for treating patients with intracanalicular punctal plug migration.


Assuntos
Granuloma , Aparelho Lacrimal , Plug Lacrimal , Adulto , Síndromes do Olho Seco , Feminino , Granuloma/etiologia , Humanos , Implantação de Prótese , Plug Lacrimal/efeitos adversos , Elastômeros de Silicone
6.
Environ Sci Process Impacts ; 21(12): 2020-2030, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31589229

RESUMO

The silicone rubber passive sampling technique is extensively applied to monitor the aqueous freely dissolved concentration of hydrophobic organic compounds (HOCs). The silicone rubber-water partition coefficient (Ksrw) is an important parameter to accurately measure the concentrations of chemicals using passive sampling devices. In this study, two theoretical linear solvation energy relationship (TLSER) models and a quantitative structure-property relationship (QSPR) model were developed for predicting the Ksrw of HOCs. The 119 model compounds studied here included 31 personal care products, such as musks, UV-filters, and organophosphate flame retardants, as well as "conventional" pollutants, such as polycyclic aromatic hydrocarbons and polychlorinated biphenyls. The statistical parameters indicated that the final QSPR model with seven descriptors for all 119 chemicals had a satisfactory goodness-of-fit (Radj2 = 0.898), robustness (QLOO2 = 0.881) and predictive ability (Qext-F1,2,32 = 0.897-0.926). In comparison, the results of one TLSER model with four descriptors for 113 chemicals (Radj2 = 0.826, QLOO2 = 0.790, Qext-F1,2,32 = 0.805-0.837) and another TLSER model with one descriptor for 5 chemicals (Radj2 = 0.747, QLOO2 = 0.647) were also acceptable. The applicability domains of the obtained models covered chemicals containing hydroxyl, imino groups, carbonyl groups, ether bonds, halogen atoms, sulfur atoms, phosphorus atoms, nitro groups, and cyano groups. In addition, the structural features governing the partition behavior of chemicals between silicone rubber and water were explored through interpretation of appropriate mechanisms.


Assuntos
Monitoramento Ambiental/métodos , Modelos Teóricos , Compostos Orgânicos/análise , Elastômeros de Silicone/química , Poluentes Químicos da Água/análise , Água/química , Monitoramento Ambiental/instrumentação , Retardadores de Chama/análise , Interações Hidrofóbicas e Hidrofílicas , Modelos Lineares , Compostos Orgânicos/química , Bifenilos Policlorados/análise , Bifenilos Policlorados/química , Hidrocarbonetos Policíclicos Aromáticos/análise , Hidrocarbonetos Policíclicos Aromáticos/química , Relação Quantitativa Estrutura-Atividade , Poluentes Químicos da Água/química
7.
Expert Rev Clin Pharmacol ; 12(10): 953-963, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31526281

RESUMO

Introduction: This is an overview of the recently FDA-approved silicone elastomer combined hormonal contraceptive vaginal ring (CVR), which is used cyclically for up to 1 year, eliminating resupply challenges. This ring requires no refrigeration, simplifying the supply chain. Developed by the Population Council, this CVR will soon be marketed in the United States as Annovera™ by TherapeuticsMD. Areas Covered: The composition of the elastomer ring and the chemical, pharmacokinetic and pharmacodynamic properties of both hormonal components are discussed. Results of the clinical trials of its efficacy, tolerability, safety, and acceptability follow. Finally, subanalyses from the clinical trials are presented to guide clinicians in counseling potential users. Expert Opinion: This CVR introduces a new progestin - segesterone acetate (SA) - that has no androgenic or estrogenic action in vitro or in vivo, but has the highest anti-ovulatory potential of all available progestins. SA is paired with EE in an intravaginal elastomer ring, that is used cyclically (21 days in place/7 days removed) to provide 12 months (13 cycles) of contraception. This once-a-month, self-applied CVR offers a convenient, rapidly reversible, year-long contraception with efficacy and side effect profiles similar to other combined hormonal methods, for women with BMI < 29 kg/m2.


Assuntos
Dispositivos Anticoncepcionais Femininos , Etinilestradiol/administração & dosagem , Contracepção Reversível de Longo Prazo , Pregnenodionas/administração & dosagem , Animais , Aprovação de Drogas , Etinilestradiol/efeitos adversos , Feminino , Humanos , Pregnenodionas/efeitos adversos , Elastômeros de Silicone/química , Estados Unidos , United States Food and Drug Administration
8.
Int J Mol Sci ; 20(17)2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31461970

RESUMO

Hybrid magnetorheological elastomers (hMREs) were manufactured based on silicone rubber, silicone oil, carbonyl iron microparticles, graphene nanoparticles and cotton fabric. Using the hMREs, flat capacitors (FCs) were made. Using the installation described in this paper, the electrical capacitance and the coefficient of dielectric losses of the hMREs were measured as a function of the intensity of the magnetic field superimposed over an alternating electric field. From the data obtained, the electrical conductivity, the relative dielectric permittivity and magnetodielectric effects are determined. It is observed that the obtained quantities are significantly influenced by the intensity of the magnetic field and the amount of graphene used.


Assuntos
Condutividade Elétrica , Grafite/química , Campos Magnéticos , Nanopartículas/química , Elastômeros de Silicone/química , Membranas Artificiais , Reologia/métodos , Suspensões/química
9.
Int J Pharm ; 569: 118574, 2019 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-31352053

RESUMO

With a dapivirine-releasing vaginal ring having successfully completed late-stage clinical testing for HIV prevention and currently undergoing regulatory review, there is now growing interest in next-generation multipurpose prevention technologies that seek to combine antiretroviral and contraceptive drugs within a single product. Here, we focus on ongoing efforts to develop a silicone elastomer vaginal ring releasing both dapivirine and levonorgestrel. Specifically, we evaluate various strategies aimed at both better understanding and reducing the tendency of levonorgestrel to bind with the elastomer, including: (i) formulation and post-manufacturing strategies aimed at reducing the extent of levonorgestrel reaction with addition-cure silicone elastomers; (ii) evaluation of a simple silicone system to model the complex elastomer; (iii) use of model compounds representing the enone and ethinyl moieties of levonorgestrel to probe the mode of addition of levonorgestrel to addition-cure silicone elastomers; and (iv) solution and solid-state 13C NMR analysis to probe the structural features of the levonorgestrel-silicone system. The results demonstrate that both the enone and ethinyl groups within levonorgestrel undergo hydrosilylation reactions with the hydrosiloxane groups in the silicone elastomer leading to covalent binding. The results also highlight potential strategies for further optimising the dapivirine + levonorgestrel silicone vaginal ring formulation to ensure that the levonorgestrel is available for release.


Assuntos
Fármacos Anti-HIV/química , Anticoncepcionais Femininos/química , Dispositivos Anticoncepcionais Femininos , Levanogestrel/química , Pirimidinas/química , Elastômeros de Silicone/química
10.
BMC Oral Health ; 19(1): 122, 2019 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-31217006

RESUMO

BACKGROUND: The inherent colour change in maxillofacial silicone elastomers becomes perceptible 6-12 months after fabrication. Determining the factors that accelerate the degradation of the prosthesis can help the clinicians increase its life span. Therefore, the aim of the study was to investigate the effect of time passage, processing temperature, and molding-stone colour on the colour change of maxillofacial silicone elastomers after darkroom storage for 6000 h. METHODS: A total of ten study molds, each incorporating ten specimen gaps were fabricated using five different colors of dental stones. The gaps were filled with coloured Cosmesil M511 maxillofacial silicone elastomer. Five of the study molds, one of each stone color, were processed at room temperature (25 °C) for 24 h while the remainder were vulcanized at 100 °C for 1 h. Two stainless-steel molds were also fabricated to obtain a total of twenty control-group specimens of the same dimensions that were processed under the same conditions as the study molds. Colour measurements of the vulcanized silicone samples were performed using a Konica Minolta spectrophotometer. Initial measurements were obtained after the blocks were removed from the molds and the final measurements were recorded 6000 h after storage in the dark at 25 °C and 40% relative humidity. The CIEDE2000 colour-difference formula was used to measure the changes in the colour. One-way and two-way ANOVA, and an independent-sample t-test were used for statistical assessments. RESULTS: For every group, the colour change exceeded the perceptible thresholds. Thus, either the vulcanization temperature or the colour of the molding stone has a significant effect on the colour change over time. Those samples vulcanized in green and white molding stones at 100 °C exhibited a significantly higher ∆L*, ∆a*, and ∆b* values relative to the samples vulcanized at room temperature. CONCLUSION: The molding-stone colour and vulcanization temperature both affect the degree of colour change after storage in a dark environment. The L*, a*, and b* values for the maxillofacial silicone elastomers are influenced by the direction of the increase or decrease according to the selected colour. This effect varies as the temperature increases.


Assuntos
Cor , Teste de Materiais , Prótese Maxilofacial , Elastômeros de Silicone/química , Humanos , Temperatura , Fatores de Tempo
11.
Indian J Ophthalmol ; 67(7): 1143-1147, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31238430

RESUMO

Purpose: External dacryocystorhinostomy (DCR) surgeries are cost-effective with excellent success rates. The present study was designed to compare the safety and efficacy of conventional external DCR versus external DCR using Pawar silicone implant in chronic dacryocystitis. Methods: This is a prospective, comparative, interventional case series over a period of 18 months with patients managed by external DCR surgery with and without Pawar implant. Institutional review board approval was obtained before the study. The success of the surgery was objectively measured by sac patency on syringing at the last follow up. Results: A total of 65 patients with chronic dacryocystitis were included in the study. The mean age of patients in the series was 41.43 years (median, 41 years; range, 12 years-60 years). All patients presented with epiphora (100%) and underwent external DCR and were chosen for conventional surgery (n = 33, 51%, group 1) or Pawar silicone implant surgery (n = 32, 49%, group 2) on a random basis. The mean duration of the surgery from the time of skin incision to skin closure for group 1 was 27.7 minutes (median, 26 minutes; range, 21-30 minutes) while in group 2, it was 75.5 minutes (median, 75 minutes; range, 60-88 minutes), which was statistically significant (P < 0.01). The success rate of the procedure done in group 1 was 90% which increased to 97% after the management of failed cases as compared to the success rate in group 2 of 91% and 94%, before and after the management of failed cases, respectively. Conclusion: External DCR using Pawar implant is a safe surgery which is faster than conventional external DCR with almost equal success rates between both the procedures.


Assuntos
Dacriocistite/cirurgia , Dacriocistorinostomia/métodos , Ducto Nasolacrimal/cirurgia , Implantação de Prótese/métodos , Elastômeros de Silicone , Adolescente , Adulto , Criança , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Desenho de Prótese , Adulto Jovem
12.
Indian J Ophthalmol ; 67(7): 1155-1157, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31238434

RESUMO

Myopic strabismus fixus causes inability of the eye to elevate and abduct in the setting of a myopic superotemporally herniated globe. We report a novel surgical technique to manage an 18-year-old male with myopic strabismus fixus. Radiological imaging demonstrated a nasally deviated superior rectus (SR) and inferiorly displaced lateral rectus (LR). Silicone band assisted myopexy of SR and LR was done along with anchoring them to the sclera with a dacron suture. The patient had satisfactory alignment postoperatively and did not require any intervention over 1-year follow-up.


Assuntos
Movimentos Oculares/fisiologia , Miopia/cirurgia , Músculos Oculomotores/cirurgia , Procedimentos Cirúrgicos Oftalmológicos/métodos , Elastômeros de Silicone , Estrabismo/cirurgia , Técnicas de Sutura/instrumentação , Adolescente , Humanos , Masculino , Miopia/complicações , Miopia/fisiopatologia , Músculos Oculomotores/fisiopatologia , Estrabismo/complicações , Estrabismo/fisiopatologia
13.
Opt Express ; 27(12): 16635-16649, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-31252887

RESUMO

Acoustic wave velocity measurement based on optical coherence tomography (OCT) is a promising approach to assess the mechanical properties of biological tissues and soft materials. While studies to date have demonstrated proof of concept of different ways to excite and detect mechanical waves, the quantitative performance of this modality as mechanical measurement has been underdeveloped. Here, we investigate the frequency dependent measurement of the wave propagation in viscoelastic tissues, using a piezoelectric point-contact probe driven with various waveforms. We found that a frequency range of 2-10 kHz is a good window for corneal elastography, in which the lowest-order flexural waves can be identified in post processing. We tested our system on tissue-simulating phantoms and ex vivo porcine eyes, and demonstrate reproducibility and inter-sample variability. Using the Kelvin-Voigt model of viscoelasticity, we extracted the shear-elastic modulus and viscosity of the cornea and their correlation with the corneal thickness, curvature, and eyeball mass. Our results show that our method can be a quantitative, useful tool for the mechanical analysis of the cornea.


Assuntos
Córnea/fisiologia , Módulo de Elasticidade , Técnicas de Imagem por Elasticidade/métodos , Tomografia de Coerência Óptica/métodos , Animais , Modelos Teóricos , Elastômeros de Silicone/química , Suínos , Viscosidade
14.
Bioinspir Biomim ; 14(4): 046005, 2019 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-31075783

RESUMO

Microstructured (sometimes referred to as gecko-like) adhesives have numerous advantages over flat films, especially for practical applications on non-ideal surfaces that may be uneven or contaminated with dust. However, due to interdependence among material surface and bulk properties, the best material to fabricate such adhesives is still unknown. In this work, we analyzed eleven commercially available silicone elastomers to evaluate their use as flat and microstructured adhesives to address multiple material related questions that may impact the choice of the 'best' material for microstructured dry adhesives. To illustrate the applicability of the measured properties to modeling microstructured surfaces, we use stalk-shaped microstructures, whose contact mechanics are well understood. We demonstrate that there is no correlation between the adhesion strength of flat and microstructured adhesives; while bulk dissipation is the most important factor influencing the adhesion strength of flat elastomers, after microstructurization, interface toughness becomes more important. Therefore, microstructured elastomers loaded with high surface energy additives may demonstrate higher adhesion than their flat counterparts. We also compare the adhesion of flat and microstructured silicone elastomers on rough substrates. In this case, we show that while flat elastomer adhesion decreases with increasing substrate roughness, microstructured silicone adhesion actually increases with increasing roughness up to 0.19 [Formula: see text]m. This is the first time an increase in adhesion strength on rough surfaces is reported for materials stiffer than 1.0 MPa.


Assuntos
Adesivos/análise , Teste de Materiais/métodos , Elastômeros de Silicone/análise , Adesivos/química , Fenômenos Biomecânicos , Biomimética , Resistência ao Cisalhamento , Elastômeros de Silicone/química , Propriedades de Superfície
15.
J Pediatr Ophthalmol Strabismus ; 56(3): 188-193, 2019 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-31116868

RESUMO

PURPOSE: To assess the success rate of external dacryocystorhinostomy (DCR) with silicone intubation for recurrent lacrimal abscess in children younger than 6 years. METHODS: A single-center retrospective analysis of 46 eyes of 40 children who underwent DCR with silicone tube intubation for recurrent lacrimal abscess was done. Probing done previously in these cases was unsuccessful. Only those children who underwent incision and drainage of the abscess at least once with antibiotic treatment were included in the study. In all cases, silicone tube removal was done after 3 months. A successful outcome was defined as the absence of subjective complaints of pain and swelling over the medial canthal area and watering and discharge at 6 months postoperatively. Objective assessment of patency of the lacrimal apparatus was done by sac syringing at 6 months postoperatively. RESULTS: The mean age at surgery was 4.93 ± 0.93 years (range: 3 to 6 years) and the mean follow-up duration was 11.80 ± 11.87 months (range: 6 to 84 months). Intra-operative difficulties encountered were excessive perisac adhesion (n = 28) and severe bleeding/hemorrhage (n = 24). A total of 82.61% cases had a successful outcome after DCR with silicon tube intubation. One child had granuloma formation at the wound. Spontaneous tube extrusion occurred in three children. CONCLUSIONS: DCR with silicone tube intubation is a safe and effective surgical approach with satisfactory outcomes for treating recurrent lacrimal abscess with congenital nasolacrimal duct obstruction in children younger than 6 years. [J Pediatr Ophthalmol Strabismus. 2019;56(3):188-193.].


Assuntos
Abscesso/cirurgia , Dacriocistorinostomia/métodos , Infecções Oculares Bacterianas/cirurgia , Intubação/instrumentação , Obstrução dos Ductos Lacrimais/congênito , Ducto Nasolacrimal/cirurgia , Elastômeros de Silicone , Abscesso/etiologia , Criança , Pré-Escolar , Infecções Oculares Bacterianas/etiologia , Feminino , Seguimentos , Humanos , Obstrução dos Ductos Lacrimais/complicações , Masculino , Ducto Nasolacrimal/anormalidades , Período Pós-Operatório , Estudos Retrospectivos , Fatores de Tempo , Resultado do Tratamento
16.
Appl Biochem Biotechnol ; 189(1): 217-232, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30972705

RESUMO

This study firstly introduced a silicone rubber membrane (SRM) into microbial fuel cell (MFC) for passive oxygen supply to simultaneously remove phenol and nitrogen from synthetic coke-oven wastewater diluted with seawater. Passive oxygen transport with biofilm on the membrane was improved by ~ 18-fold in comparison with the one without a biofilm. In addition, although the oxygen supply was passive, nitrification accounted for 34% of those aeration conditions. It was also found that silicone rubber membrane can control NO2--N and/or NO3--N production. A dual-chamber MFC treating the synthetic coke-oven wastewater achieved a maximum power density of 54 mW m-2 with a coulombic efficiency of 2.7%. We conclude that silicone rubber membrane is effective for sustainable coke-oven wastewater treatment in MFCs.


Assuntos
Fontes de Energia Bioelétrica , Carbono/administração & dosagem , Membranas Artificiais , Nitrogênio/administração & dosagem , Oxigênio/administração & dosagem , Elastômeros de Silicone/química
17.
J Prosthet Dent ; 122(2): 168-175, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30928225

RESUMO

STATEMENT OF PROBLEM: Maxillofacial elastomers undergo physical and mechanical degradation with disinfecting solutions. Solutions of Brazilian green propolis extract may be suitable alternatives for infection control of maxillofacial prostheses. However, their effects on the properties of the material are unknown. PURPOSE: The purpose of this in vitro study was to evaluate the effect of disinfection with solutions of Brazilian green propolis extract on the transmittance, translucency parameter, contrast ratio, and hardness of 2 maxillofacial elastomers (MDX4-4210 and MED-4014). MATERIAL AND METHODS: Fifty disk-shaped specimens (3×10 mm) of each elastomer were randomly and equally divided into 4 groups of disinfectant agents and 1 control group: 3 separate groups of 11% green propolis extracts including aqueous (PAQ), glycolic (PGL), and alcoholic (PAL), a 2% chlorhexidine gluconate (CHX) group, and the control group of distilled water. Specimens were subjected to disinfection by immersion 3 times a week for 60 days. Color differences (ΔE values) were calculated with CIELab and CIEDE2000 formulas. Optical parameters and Shore A hardness were determined at 2 time points: at baseline and after the period of specimen disinfection. Data were analyzed by parametric and nonparametric analysis of variance and by multiple-comparison tests (α=.05). RESULTS: The ΔE values of specimens immersed in 11% PAL were not clinically acceptable for either elastomer. Regarding translucency parameter and contrast ratio, the immersion in 11% PAL and 11% PGL resulted in greater opacity and lower translucency of the material. Mean Shore A hardness values were not statistically significantly different at baseline or after 60 days of immersion in the solutions. CONCLUSIONS: The solution of Brazilian green propolis extract tested showed changes in optical parameters. Elastomers immersed in 11% alcoholic green propolis extract showed clinically unacceptable color and translucency changes. All hardness values of the tested elastomers were clinically acceptable after immersion in all tested disinfectant groups.


Assuntos
Prótese Maxilofacial , Própole , Brasil , Cor , Elastômeros , Dureza , Imersão , Teste de Materiais , Extratos Vegetais , Elastômeros de Silicone
18.
PLoS One ; 14(3): e0210570, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30865622

RESUMO

In mammalian cells, actin, microtubules, and various types of cytoplasmic intermediate filaments respond to external stretching. Here, we investigated the underlying processes in endothelial cells plated on soft substrates from silicone elastomer. After cyclic stretch (0.13 Hz, 14% strain amplitude) for periods ranging from 5 min to 8 h, cells were fixed and double-stained for microtubules and either actin or vimentin. Cell images were analyzed by a two-step routine. In the first step, micrographs were segmented for potential fibrous structures. In the second step, the resulting binary masks were auto- or cross-correlated. Autocorrelation of segmented images provided a sensitive and objective measure of orientational and translational order of the different cytoskeletal systems. Aligning of correlograms from individual cells removed the influence of only partial alignment between cells and enabled determination of intrinsic cytoskeletal order. We found that cyclic stretching affected the actin cytoskeleton most, microtubules less, and vimentin mostly only via reorientation of the whole cell. Pharmacological disruption of microtubules had barely any influence on actin ordering. The similarity, i.e., cross-correlation, between vimentin and microtubules was much higher than the one between actin and microtubules. Moreover, prolonged cyclic stretching slightly decoupled the cytoskeletal systems as it reduced the cross-correlations in both cases. Finally, actin and microtubules were more correlated at peripheral regions of cells whereas vimentin and microtubules correlated more in central regions.


Assuntos
Citoesqueleto/fisiologia , Células Endoteliais/citologia , Estresse Mecânico , Actinas/química , Algoritmos , Células Endoteliais da Veia Umbilical Humana , Humanos , Microtúbulos/química , Elastômeros de Silicone/química , Vimentina/química
19.
Acta Ophthalmol ; 97(6): e860-e870, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30900825

RESUMO

PURPOSE: To reduce capsular opacification by a peri-surgical treatment of the lens capsule with drugs in an in vivo rabbit model. Lens-refilling surgery is a potential therapeutic intervention to treat patients with a cataract lens. The lens material is replaced with an injectable (bio)polymer that retains the natural mechanical and optical lens properties, therewith allowing accommodation. The occurrence of capsular opacification mediated by lens epithelial cells negatively affects accommodation and vision and should be avoided in this lens restoration approach. METHODS: An in vivo rabbit animal model was used with lens replacement with a silicone-based gel-like polymer and concurrent treatment of the lens epithelium with drugs. A case-study approach was applied as both drug combinations and implantation times were varied. The following drugs were investigated for their potential to prevent capsular opacification long-term: actinomycin D, methotrexate, paclitaxel and Tween-20. All were administered in a hyaluronic acid vehicle. The rabbits were clinically followed for periods up to 4 years postimplantation. Eyes, corneas and lenses were analysed post-mortem using MRI and confocal microscopy. RESULTS: Treatment combinations containing actinomycin D generally led to the least appearance of capsular fibrosis. The use of Tween-20 or paclitaxel without actinomycin D resulted in much earlier and pronounced fibrotic responses. The aspect of capsular opacification was highly variable in individual animals. Application of the drugs in a hyaluronic acid vehicle appeared to be a safe method that spared the corneal endothelium. CONCLUSION: The feasibility of long-term prevention of fibrosis over a period of more than 4 years has been demonstrated in lens refilling in the rabbit model.


Assuntos
Opacificação da Cápsula/prevenção & controle , Catarata/fisiopatologia , Cápsula do Cristalino/cirurgia , Lentes Intraoculares , Facoemulsificação/efeitos adversos , Refração Ocular/fisiologia , Elastômeros de Silicone , Acomodação Ocular , Animais , Opacificação da Cápsula/etiologia , Modelos Animais de Doenças , Estudos de Viabilidade , Seguimentos , Cristalino/cirurgia , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/prevenção & controle , Desenho de Prótese , Coelhos , Fatores de Tempo
20.
Plast Reconstr Surg ; 143(6): 1290e-1297e, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30907812

RESUMO

BACKGROUND: Face transplant teams have an ethical responsibility to restore the donor's likeness after allograft procurement. This has been achieved with masks constructed from facial impressions and three-dimensional printing. The authors compare the accuracy of conventional impression and three-dimensional printing technology. METHODS: For three subjects, a three-dimensionally-printed mask was created using advanced three-dimensional imaging and PolyJet technology. Three silicone masks were made using an impression technique; a mold requiring direct contact with each subject's face was reinforced by plaster bands and filled with silicone. Digital models of the face and both masks of each subject were acquired with Vectra H1 Imaging or Artec scanners. Each digital mask model was overlaid onto its corresponding digital face model using a seven-landmark coregistration; part comparison was performed. The absolute deviation between each digital mask and digital face model was compared with the Mann-Whitney U test. RESULTS: The absolute deviation (in millimeters) of each digitally printed mask model relative to the digital face model was significantly smaller than that of the digital silicone mask model (subject 1, 0.61 versus 1.29, p < 0.001; subject 2, 2.59 versus 2.87, p < 0.001; subject 3, 1.77 versus 4.20, p < 0.001). Mean cost and production times were $720 and 40.2 hours for three-dimensionally printed masks, and $735 and 11 hours for silicone masks. CONCLUSIONS: Surface analysis shows that three-dimensionally-printed masks offer greater surface accuracy than silicone masks. Greater donor resemblance without additional risk to the allograft may make three-dimensionally-printed masks the superior choice for face transplant teams. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.


Assuntos
Transplante de Face/métodos , Impressão Tridimensional/normas , Custos e Análise de Custo , Transplante de Face/economia , Humanos , Doadores Vivos , Impressão Tridimensional/economia , Elastômeros de Silicone/economia , Sítio Doador de Transplante , Transplante Homólogo
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