Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 55
Filtrar
1.
ACS Biomater Sci Eng ; 8(12): 5101-5109, 2022 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-36374748

RESUMEN

The addition of poly(ethylene glycol) (PEG) to biomolecules and biomaterials is a well-established approach to modify their properties for therapeutic applications. For biomaterials, the approach is typically to blend or electrospray the synthetic polymer with the biomaterial. Effective surface modification approaches such as surface-initiated polymer brushes are challenging since the harsh solvents required for brush synthesis may destroy the biomaterial. Herein, we describe the PEGylation of collagen fibers by surface-initiated PEG brushes using a living anionic grafting-from mechanism. This brush synthesis is done in the absence of solvents to minimize the degradation of the native collagen structure. We quantify the effect the brush synthesis has on the native structure of the collagen fiber using differential scanning calorimetry (DSC) and find that even at long reaction times a significant fraction of the native structure remains. Dynamic mechanical analysis indicates the collagen undergoes only modest structural degradation, while adhesion studies find a significant improvement of antifouling properties. Further, our approach opens the way for further chemistry, as the growing polymer chain is a potassium alkoxy group that can be functionalized by termination or by subsequent reaction by a wide variety of molecules.


Asunto(s)
Polietilenglicoles , Polímeros , Solventes , Polietilenglicoles/química , Materiales Biocompatibles , Colágeno
2.
JSES Int ; 6(4): 675-681, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35813136

RESUMEN

Hypothesis: The aim of this study was to investigate the reproducibility, reliability, and accuracy of Mirels' score in upper limb bony metastatic disease and validate its use in predicting pathologic fractures. Methods: Forty-five patients with upper limb bony metastases met the inclusion criteria (62% male 28/45). The mean age was 69 years (SD 9.5), and the most common primaries were lung (29%, 13/45), followed by prostate and hematological (each 20%, 9/45). The most commonly affected bone was the humerus (76%, 35/45), followed by the ulna (6.5%, 3/45). Mirels' score was calculated in 32 patients; with plain radiographs at index presentation scored using Mirels' system by 6 raters. The radiological aspects (lesion size and appearance) were scored twice by each rater (2 weeks apart). Intraobserver and interobserver reliability were calculated using Fleiss' kappa test. Bland-Altman plots compared the variances of both individual components and the total Mirels' score. Results: The overall fracture rate of upper limb metastatic lesions was 76% (35/46) with a mean follow-up of 3.6 years (range 11 months-6.8 years). Where time from diagnosis to fracture was known (n = 20), fractures occurred at a median 19 days (interquartile range 60-10), and 80% (16/20) occurred within 3 months of diagnosis.Mirels' score of ≥9 did not accurately predict lesions that fractured (fracture rate 11%, 5/46, for Mirels' ≥ 9 vs. 65%, 30/46, for Mirels' ≤ 8, P < .001). Sensitivity was 14%, and specificity was 73%. When Mirels' cutoff was lowered to ≥7, patients were more likely to fracture than not (48%, 22/46, vs. 28%, 13/46, P = .045); sensitivity rose to 63%, but specificity fell to 55%.Kappa values for interobserver variability were κ = 0.358 (fair, 95% confidence interval [CI] 0.288-0.429) for lesion size, κ = 0.107 (poor, 95% CI 0.02-0.193) for radiological appearance, and κ = 0.274 (fair, 95% CI 0.229-0.318) for total Mirels' score. Values for intraobserver variability were κ = 0.716 (good, 95% CI 0.432-0.999) for lesion size, κ = 0.427 (moderate, 95% CI 0.195-0.768) for radiological appearance, and κ = 0.580 (moderate, 95% CI 0.395-0.765) for total Mirels' score. Conclusions: This study demonstrates moderate to substantial agreement between and within raters using Mirels' score on upper limb radiographs. However, Mirels' score had a poor sensitivity and specificity in predicting upper extremity fractures. Until a more valid scoring system has been developed, based on our study, we recommend a Mirels' threshold of ≥7/12 for considering prophylactic fixation of impending upper limb pathologic fractures. This contrasts with the current ≥9/12 cutoff, which is recommended for lower limb pathologic fractures.

3.
Langmuir ; 37(31): 9378-9384, 2021 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-34323491

RESUMEN

A chromatographic approach for separating exfoliated graphene from natural flake graphite is presented. Graphene is an extremely strong, electrically and thermally conductive two-dimensional hexagonal array of carbon atoms with the potential to transform applications such as supercapacitors, composites, biosensors, ultra-thin touchscreens, and solar cells. However, many of these applications require the use of exfoliated graphene, and the current cost of this material can be prohibitive. The most cost-effective source of graphene is exfoliated graphite, and numerous approaches have been proposed for exfoliating graphite to graphene. Solution approaches are the most common, with graphite often exfoliated by extended sonication treatment followed by separation of graphene from graphite using centrifugation. This time-consuming approach results in low concentrations of small lateral dimension graphene, often in high-boiling-point organic solvents or containing stabilizers. In this study, a chromatographic approach is used in combination with a solvent interface trapping method of graphite exfoliation to isolate graphene. The interface trapping exfoliation approach uses a hydrophobic/hydrophilic solvent interface to spontaneously exfoliate graphite and form a graphene-stabilized water-in-oil emulsion. This emulsion contains both graphene and graphite, and when added to water-wet glass beads, graphene adsorbs onto the glass surface, leaving graphite in the hydrophobic mobile phase, where it is removed by washing with an additional oil phase. The efficiency of this scalable approach to separation is demonstrated by Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and Tyndall effect scattering.

5.
Health Technol Assess ; 25(31): 1-144, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-34042566

RESUMEN

BACKGROUND: Most patients with oesophageal cancer present with incurable disease. For those with advanced disease, the mean survival is 3-5 months. Treatment emphasis is therefore on effective palliation, with the majority of patients requiring intervention for dysphagia. Insertion of a self-expanding metal stent provides rapid relief but dysphagia may recur within 3 months owing to tumour progression. Evidence reviews have called for trials of interventions combined with stenting to better maintain the ability to swallow. OBJECTIVES: The Radiotherapy after Oesophageal Cancer Stenting (ROCS) study examined the effectiveness of palliative radiotherapy, combined with insertion of a stent, in maintaining the ability to swallow. The trial also examined the impact that the ability to swallow had on quality of life, bleeding events, survival and cost-effectiveness. DESIGN: A pragmatic, multicentre, randomised controlled trial with follow-up every 4 weeks for 12 months. An embedded qualitative study examined trial experiences in a participant subgroup. SETTING: Participants were recruited in secondary care, with all planned follow-up at home. PARTICIPANTS: Patients who were referred for stent insertion as the primary management of dysphagia related to incurable oesophageal cancer. INTERVENTIONS: Following stent insertion, the external beam radiotherapy arm received palliative oesophageal radiotherapy at a dose of 20 Gy in five fractions or 30 Gy in 10 fractions. MAIN OUTCOME MEASURES: The primary outcome was the difference in the proportion of participants with recurrent dysphagia, or death, at 12 weeks. Recurrent dysphagia was defined as deterioration of ≥ 11 points on the dysphagia scale of the European Organisation of Research and Treatment of Cancer Quality of Life Questionnaire oesophago-gastric module questionnaire. Secondary outcomes included quality of life, bleeding risk and survival. RESULTS: The study recruited 220 patients: 112 were randomised to the usual-care arm and 108 were randomised to the external beam radiotherapy arm. There was no evidence that radiotherapy reduced recurrence of dysphagia at 12 weeks (48.6% in the usual-care arm compared with 45.3% in the external beam radiotherapy arm; adjusted odds ratio 0.82, 95% confidence interval 0.40 to 1.68; p = 0.587) and it was less cost-effective than stent insertion alone. There was no difference in median survival or key quality-of-life outcomes. There were fewer bleeding events in the external beam radiotherapy arm. Exploration of patient experience prompted changes to trial processes. Participants in both trial arms experienced difficulty in managing the physical and psychosocial aspects of eating restriction and uncertainties of living with advanced oesophageal cancer. LIMITATIONS: Change in timing of the primary outcome to 12 weeks may affect the ability to detect a true intervention effect. However, consistency of results across sensitivity analyses is robust, including secondary analysis of dysphagia deterioration-free survival. CONCLUSIONS: Widely accessible palliative external beam radiotherapy in combination with stent insertion does not reduce the risk of dysphagia recurrence at 12 weeks, does not have an impact on survival and is less cost-effective than inserting a stent alone. Reductions in bleeding events should be considered in the context of patient-described trade-offs of fatigue and burdens of attending hospital. Trial design elements including at-home data capture, regular multicentre nurse meetings and qualitative enquiry improved recruitment/data capture, and should be considered for future studies. FUTURE WORK: Further studies are required to identify interventions that improve stent efficacy and to address the multidimensional challenges of eating and nutrition in this patient population. TRIAL REGISTRATION: Current Controlled Trials ISRCTN12376468 and Clinicaltrials.gov NCT01915693. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 31. See the NIHR Journals Library website for further project information.


Most people are diagnosed with oesophageal (gullet) cancer when it is already at an advanced stage. Losing the ability to swallow food and even fluids is very common when patients are approaching the last months of life. Placing a flexible metal tube, or stent, in the gullet opens it up and improves the ability to swallow quickly. Unfortunately this can fail after around 3 months because the cancer grows and presses on the stent. We designed this trial to see if giving a small dose of radiotherapy alongside insertion of the stent would allow more people to remain swallowing well after 3 months. This could then improve their quality of life and reduce hospitalisation towards the end of life. It may also reduce bleeding from the gullet, as well as other symptoms. We recruited 220 people across the UK, randomly assigning them to have the stent as usual or the stent and a low dose of radiotherapy. We collected a lot of information from the participants at home on how the cancer, the stent and the radiotherapy affected their ability to swallow and their quality of life. Overall, the study showed that the radiotherapy did not improve the ability to swallow 3 months following stent insertion and was less cost-effective than stent insertion alone. It seemed to reduce the risk of bleeding from the tumour itself, but patients found that radiotherapy made them tired and attending extra hospital visits could be troublesome. We also learned that, even after a stent was inserted, patients still struggled with food and needed more support with managing daily life with the stent. The trial results are important. They show that, to answer questions such as these, studies should use different ways of assessing what works, particularly focusing on patients' and families' viewpoints. The results will guide doctors to not routinely give radiotherapy in this situation. The results also suggest that, after the insertion of a stent, patients need extra help in managing their diet, their worries about the stent and their worries about the future.


Asunto(s)
Trastornos de Deglución , Neoplasias Esofágicas , Análisis Costo-Beneficio , Trastornos de Deglución/etiología , Neoplasias Esofágicas/complicaciones , Neoplasias Esofágicas/radioterapia , Humanos , Recurrencia Local de Neoplasia/radioterapia , Calidad de Vida , Stents
6.
J Appl Clin Med Phys ; 22(4): 26-33, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33689216

RESUMEN

BACKGROUND AND PURPOSE: When planning and delivering radiotherapy, ideally bolus should be in direct contact with the skin surface. Varying air gaps between the skin surface and bolus material can result in discrepancies between the intended and delivered dose. This study assessed a three-dimensional (3D) printed flexible bolus to determine whether it could improve conformity to the skin surface, reduce air gaps, and improve planning target volume coverage, compared to a commercial bolus material, Superflab. MATERIALS AND METHODS: An anthropomorphic head phantom was CT scanned to generate photon and electron treatment plans using virtual bolus. Two 3D printing companies used the material Ninjaflex to print bolus for the head phantom, which we designated Ninjaflex1 and Ninjaflex2. The phantom was scanned a further 15 more times with the different bolus materials in situ allowing plan comparison of the virtual to physical bolus in terms of planning target volume coverage, dose at the prescription point, skin dose, and air gap volumes. RESULTS: Superflab produced a larger volume and a greater number of air gaps compared to both Ninjaflex1 and Ninjaflex2, with the largest air gap volume of 12.02 cm3 . Our study revealed that Ninjaflex1 produced the least variation from the virtual bolus clinical goal values for all modalities, while Superflab displayed the largest variances in conformity, positional accuracy, and clinical goal values. For PTV coverage Superflab produced significant percentage differences for the VMAT and Electron3 plans when compared to the virtual bolus plans. Superflab also generated a significant difference in prescription point dose for the 3D conformal plan. CONCLUSION: Compared to Superflab, both Ninjaflex materials improved conformity and reduced the variance between the virtual and physical bolus clinical goal values. Results illustrate that custom-made Ninjaflex bolus could be useful clinically and may improve the accuracy of the delivered dose.


Asunto(s)
Planificación de la Radioterapia Asistida por Computador , Radioterapia de Intensidad Modulada , Humanos , Fantasmas de Imagen , Radiometría , Dosificación Radioterapéutica , Reproducibilidad de los Resultados
7.
Lancet Gastroenterol Hepatol ; 6(4): 292-303, 2021 04.
Artículo en Inglés | MEDLINE | ID: mdl-33610215

RESUMEN

BACKGROUND: Patients with advanced oesophageal cancer have a median survival of 3-6 months, and most require intervention for dysphagia. Self-expanding metal stent (SEMS) insertion is the most typical form of palliation in these patients, but dysphagia deterioration and re-intervention are common. This study examined the efficacy of adjuvant external beam radiotherapy (EBRT) compared with usual care alone in preventing dysphagia deterioration and reducing service use after SEMS insertion. METHODS: This was a multicentre, open-label, phase 3 randomised controlled trial based at cancer centres and acute care hospitals in England, Scotland, and Wales. Patients (aged ≥16 years) with incurable oesophageal carcinoma receiving stent insertion for primary management of dysphagia were randomly assigned (1:1) to receive usual care alone or EBRT (20 Gy in five fractions or 30 Gy in ten fractions) plus usual care after stent insertion. Usual care was implemented according to need as identified by the local multidisciplinary team (MDT). Randomisation was via the method of minimisation stratified by treating centre, stage at diagnosis (I-III vs IV), histology (squamous or non-squamous), and MDT intent to give chemotherapy (yes vs no). The primary outcome was difference in proportions of participants with dysphagia deterioration (>11 point decrease on patient-reported European Organisation for Research and Treatment of Cancer quality of life questionnaire-oesophagogastric module [QLQ-OG25], or a dysphagia-related event consistent with such a deterioration) or death by 12 weeks in a modified intention-to-treat (ITT) population, which excluded patients who did not have a stent inserted and those without a baseline QLQ-OG25 assessment. Secondary outcomes included survival, quality of life (QoL), morbidities (including time to first bleeding event or hospital admission for bleeding event and first dysphagia-related stent complications or re-intervention), and cost-effectiveness. Safety analysis was undertaken in the modified ITT population. The study is registered with the International Standard Randomised Controlled Trial registry, ISRCTN12376468, and ClinicalTrials.gov, NCT01915693, and is completed. FINDINGS: 220 patients were randomly assigned between Dec 16, 2013, and Aug 24, 2018, from 23 UK centres. The modified ITT population (n=199) comprised 102 patients in the usual care group and 97 patients in the EBRT group. Radiotherapy did not reduce dysphagia deterioration, which was reported in 36 (49%) of 74 patients receiving usual care versus 34 (45%) of 75 receiving EBRT (adjusted odds ratio 0·82 [95% CI 0·40-1·68], p=0·59) in those with complete data for the primary endpoint. No significant difference was observed in overall survival: median overall survival was 19·7 weeks (95% CI 14·4-27·7) with usual care and 18·9 weeks (14·7-25·6) with EBRT (adjusted hazard ratio 1·06 [95% CI 0·78-1·45], p=0·70; n=199). Median time to first bleeding event or hospital admission for a bleeding event was 49·0 weeks (95% CI 33·3-not reached) with usual care versus 65·9 weeks (52·7-not reached) with EBRT (adjusted subhazard ratio 0·52 [95% CI 0·28-0·97], p=0·038; n=199). No time versus treatment interaction was observed for prespecified QoL outcomes. We found no evidence of differences between trial group in time to first stent complication or re-intervention event. The most common (grade 3-4) adverse event was fatigue, reported in 19 (19%) of 102 patients receiving usual care alone and 22 (23%) of 97 receiving EBRT. On cost-utility analysis, EBRT was more expensive and less efficacious than usual care. INTERPRETATION: Patients with advanced oesophageal cancer having SEMS insertion for the primary management of their dysphagia did not gain additional benefit from concurrent palliative radiotherapy and it should not be routinely offered. For a minority of patients clinically considered to be at high risk of tumour bleeding, concurrent palliative radiotherapy might reduce bleeding risk and the need for associated interventions. FUNDING: National Institute for Health Research Health Technology Assessment Programme.


Asunto(s)
Neoplasias Esofágicas/terapia , Stents , Adenocarcinoma/mortalidad , Adenocarcinoma/terapia , Anciano , Anciano de 80 o más Años , Carcinoma de Células Escamosas/mortalidad , Carcinoma de Células Escamosas/terapia , Terapia Combinada , Neoplasias Esofágicas/mortalidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Cuidados Paliativos , Radioterapia , Análisis de Supervivencia , Resultado del Tratamiento , Reino Unido
8.
Breast Cancer Res ; 23(1): 8, 2021 01 15.
Artículo en Inglés | MEDLINE | ID: mdl-33451345

RESUMEN

BACKGROUND: Xentuzumab-a humanised IgG1 monoclonal antibody-binds IGF-1 and IGF-2, inhibiting their growth-promoting signalling and suppressing AKT activation by everolimus. This phase Ib/II exploratory trial evaluated xentuzumab plus everolimus and exemestane in hormone receptor-positive, locally advanced and/or metastatic breast cancer (LA/MBC). METHODS: Patients with hormone receptor-positive/HER2-negative LA/MBC resistant to non-steroidal aromatase inhibitors were enrolled. Maximum tolerated dose (MTD) and recommended phase II dose (RP2D) of xentuzumab/everolimus/exemestane were determined in phase I (single-arm, dose-escalation). In phase II (open-label), patients were randomised 1:1 to the RP2D of xentuzumab/everolimus/exemestane or everolimus/exemestane alone. Randomisation was stratified by the presence of visceral metastases. Primary endpoint was progression-free survival (PFS). RESULTS: MTD was determined as xentuzumab 1000 mg weekly plus everolimus 10 mg/day and exemestane 25 mg/day. A total of 140 patients were enrolled in phase II (70 to each arm). Further recruitment was stopped following an unfavourable benefit-risk assessment by the internal Data Monitoring Committee appointed by the sponsor. Xentuzumab was discontinued; patients could receive everolimus/exemestane if clinically indicated. Median PFS was 7.3 months (95% CI 3.3-not calculable) in the xentuzumab/everolimus/exemestane group and 5.6 months (3.7-9.1) in the everolimus/exemestane group (hazard ratio 0.97, 95% CI 0.57-1.65; P = 0.9057). In a pre-specified subgroup of patients without visceral metastases at screening, xentuzumab/everolimus/exemestane showed evidence of PFS benefit versus everolimus/exemestane (hazard ratio 0.21 [0.05-0.98]; P = 0.0293). Most common any-cause adverse events in phase II were diarrhoea (29 [41.4%] in the xentuzumab/everolimus/exemestane group versus 20 [29.0%] in the everolimus/exemestane group), mucosal inflammation (27 [38.6%] versus 21 [30.4%]), stomatitis (24 [34.3%] versus 24 [34.8%]), and asthenia (21 [30.0%] versus 24 [34.8%]). CONCLUSIONS: Addition of xentuzumab to everolimus/exemestane did not improve PFS in the overall population, leading to early discontinuation of the trial. Evidence of PFS benefit was observed in patients without visceral metastases when treated with xentuzumab/everolimus/exemestane, leading to initiation of the phase II XENERA™-1 trial (NCT03659136). TRIAL REGISTRATION: ClinicalTrials.gov, NCT02123823 . Prospectively registered, 8 March 2013.


Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/etiología , Adulto , Anciano , Anciano de 80 o más Años , Androstadienos/administración & dosificación , Anticuerpos Monoclonales Humanizados/administración & dosificación , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Biomarcadores de Tumor , Neoplasias de la Mama/diagnóstico , Neoplasias de la Mama/mortalidad , Manejo de la Enfermedad , Everolimus/administración & dosificación , Femenino , Humanos , Dosis Máxima Tolerada , Persona de Mediana Edad , Metástasis de la Neoplasia , Estadificación de Neoplasias , Pronóstico , Receptor ErbB-2 , Receptores de Estrógenos , Receptores de Progesterona , Resultado del Tratamiento
9.
Sci Rep ; 10(1): 18047, 2020 Oct 22.
Artículo en Inglés | MEDLINE | ID: mdl-33093555

RESUMEN

Paper diagnostics are of growing interest due to their low cost and easy accessibility. Conductive inks, necessary for manufacturing the next generation diagnostic devices, currently face challenges such as high cost, high sintering temperatures, or harsh conditions required to remove stabilizers. Here we report an effective, inexpensive, and environmentally friendly approach to graphene ink that is suitable for screen printing onto paper substrates. The ink formulation contains only pristine graphite, water, and non-toxic alkanes formed by an interfacial trapping method in which graphite spontaneously exfoliates to graphene. The result is a viscous graphene stabilized water-in-oil emulsion-based ink. This ink does not require sintering, but drying at 90 °C or brief microwaving can improve the conductivity. The production requires only 40 s of shaking to form the emulsion. The sheet resistance of the ink is approximately 600 Ω/sq at a thickness of less than 6 µm, and the ink can be stabilized by as little as 1 wt% graphite.

10.
J Mater Chem B ; 8(45): 10392-10406, 2020 12 07.
Artículo en Inglés | MEDLINE | ID: mdl-33112356

RESUMEN

Bombyx mori silk fibroin is a fibrous protein whose tunable properties and biocompatibility have resulted in its utility in a wide-variety of applications, including as drug delivery vehicles, wound dressings, and tissue engineering scaffolds. Control of protein and cell attachment is vital to the performance of biomaterials, but silk fibroin is mostly hydrophobic and interacts nonspecifically with cells and proteins. Silk functionalised with hydrophilic polymers reduces attachment, but the low number of reactive sites makes achieving a uniform conjugation a persistent challenge. This work presents a new approach to grow brush-like polymers from the surface of degradable silk films, where the films were enriched with hydroxyl groups, functionalised with an initiator, and finally reacted with acrylate monomers using atom transfer radical polymerisation. Two different routes to hydroxyl enrichment were investigated, one involving reaction with ethylene oxide (EO) and the other using a two-step photo-catalysed oxidation reaction. Both routes increased surface hydrophilicity, and hydrophilic monomers containing either uncharged (poly(ethylene glycol), PEG) pendant groups or zwitterionic pendant groups were polymerised from the surfaces. The initial processing of the films to induce beta sheet structures was found to impact the success of the polymerizations. Compared to the EO modified or unmodified silk surfaces, the oxidation reaction resulted in more polymer conjugation and the surfaces appear more uniform. Mesenchymal stem cell and protein attachment were the lowest on polymers grown from oxidised surfaces. PEG-containing brush-like polymers displayed lower protein attachment than surfaces conjugated with PEG using a previously reported "grafting to" method, but polymers containing zwitterionic side chains displayed both the lowest contact angles and the lowest cell and protein attachment. This finding may arise from the interactions of the zwitterionic pendant groups through their permanent dipoles and is an important finding because PEG is susceptible to oxidative damage that can reduce efficacy over time. These modified silk materials with lower cell and protein attachments are envisioned to find utility when enhanced diffusion around surfaces is required, such as in drug delivery implants.


Asunto(s)
Bombyx/química , Fibroínas/química , Polietilenglicoles/química , Andamios del Tejido/química , Animales , Adhesión Celular , Línea Celular , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Polimerizacion , Albúmina Sérica Bovina/aislamiento & purificación
11.
Langmuir ; 36(35): 10421-10428, 2020 09 08.
Artículo en Inglés | MEDLINE | ID: mdl-32794716

RESUMEN

Ion partitioning behavior in electrolyte solutions plays an important role in drug delivery and therapeutics, protein folding, materials science, filtration, and energy applications such as supercapacitors. Here, we show that the segregation of ions in solutions also plays an important role in the exfoliation of natural flake graphite to pristine graphene. Polarizable anions such as iodide and acetate segregate to the interfacial region of the aqueous phase during solvent interfacial trapping exfoliation of graphene. Ordered water layers and accumulated charges near the graphene surface aid in separating graphene sheets from bulk graphite, and, more importantly, reduce the reversibility of the exfoliation event. The observed phenomenon results not only in the improved stability of graphene-stabilized emulsions but also in a low-cost and environmentally friendly way of enhancing the production of graphene.

12.
J Colloid Interface Sci ; 580: 700-708, 2020 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-32712476

RESUMEN

Graphene is attractive as a functional 2D surfactant for polymerized high internal phase emulsions (polyHIPEs) due to its remarkable mechanical and electrical properties. We have developed polyHIPEs stabilized by pristine, unoxidized graphene via the spontaneous exfoliation of graphite at high-energy aqueous/organic interfaces. The exfoliated graphene self-assembles into a percolating network and incorporates into the polyHIPE cell walls as verified by TEM. The resulting composites showed compressive strengths of 7.0 MPa at densities of 0.22 g/cm3 and conductivities up to 0.36 S/m. Systematically reducing the concentration of monomer in the oil phase by dilution with a porogenic-acting solvent increased the porosity and lowered the density of the polyHIPEs. Characterization of these composites indicated that graphene's high compressive strength and modulus was transferred to the polyHIPEs and provided mechanical reinforcement even at low polymer content. SEM showed that the morphology of the polymer changed with decreasing monomer content while the graphene lined cells retained their shape. Moreover, we show that the polyHIPEs contain a continuous graphene percolating network resulting in electrically conductive materials at low graphene loading.

13.
ACS Appl Mater Interfaces ; 12(26): 29692-29699, 2020 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-32492330

RESUMEN

Spontaneously exfoliated pristine graphene is used as a surfactant to template the formation of electrically conductive filters for the adsorption of an organic dye from water. In contrast to other reported graphene-based adsorption materials, our system provides a continuous approach to water treatment rather than a batch approach, and uses pristine graphene instead of the more costly and environmentally challenging graphene oxide. The use of self-assembled graphene also results in our filters being electrically conductive, providing a convenient route to clean the filters by resistive heating. An investigation of the mechanism of formation and filtration by these filters, templated by self-assembled two-dimensional pristine graphene, is presented. The thermodynamically driven exfoliation of natural flake graphite at a high-energy monomer/water interface produces water-in-oil emulsions stabilized by a thin layer of overlapping graphene sheets. Subsequent polymerization of the continuous monomer phase produces polymer foams with cells lined by graphene. With a combination of acoustic spectroscopy and electron microscopy, the effects of graphite concentration and temperature are studied, as is the correlation between droplet size and the size of the cells in the final polymer foam.

14.
Bone Joint J ; 102-B(1): 72-81, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31888363

RESUMEN

AIMS: The early mortality in patients with hip fractures from bony metastases is unknown. The objectives of this study were to quantify 30- and 90-day mortality in patients with proximal femoral metastases, and to create a mortality prediction tool based on biomarkers associated with early death. METHODS: This was a retrospective cohort study of consecutive patients referred to the orthopaedic department at a UK trauma centre with a proximal femoral metastasis (PFM) over a seven-year period (2010 to 2016). The study group were compared to a matched control group of non-metastatic hip fractures. Minimum follow-up was one year. RESULTS: There was a 90-day mortality of 46% in patients with metastatic hip fractures versus 12% in controls (89/195 and 24/192, respectively; p < 0.001). Mean time to surgery was longer in symptomatic metastases versus complete fractures (9.5 days (SD 19.8) and 3.4 days (SD 11.4), respectively; p < 0.05). Albumin, urea, and corrected calcium were all independent predictors of early mortality and were used to generate a simple tool for predicting 90-day mortality, titled the Metastatic Early Prognostic (MEP) score. An MEP score of 0 was associated with the lowest risk of death at 30 days (14%, 3/21), 90 days (19%, 4/21), and one year (62%, 13/21). MEP scores of 3/4 were associated with the highest risk of death at 30 days (56%, 5/9), 90 days (100%, 9/9), and one year (100%, 9/9). Neither age nor primary cancer diagnosis was an independent predictor of mortality at 30 and 90 days. CONCLUSION: This score could be used to predict early mortality and guide perioperative counselling. The delay to surgery identifies a potential window to intervene and correct these abnormalities with the aim of improving survival. Cite this article: Bone Joint J. 2020;102-B(1):72-81.


Asunto(s)
Neoplasias Femorales/mortalidad , Adulto , Anciano , Anciano de 80 o más Años , Biomarcadores de Tumor/metabolismo , Estudios de Casos y Controles , Femenino , Neoplasias Femorales/secundario , Humanos , Masculino , Persona de Mediana Edad , Pronóstico , Estudios Retrospectivos , Escocia/epidemiología , Índice de Severidad de la Enfermedad , Análisis de Supervivencia , Tiempo de Tratamiento
15.
Cancer Imaging ; 19(1): 91, 2019 Dec 26.
Artículo en Inglés | MEDLINE | ID: mdl-31878958

RESUMEN

BACKGROUND: In patients who have had axillary nodal metastasis diagnosed prior to neoadjuvant chemotherapy for breast cancer, there is little consensus on how to manage the axilla subsequently. The aim of this study was to explore whether a combination of breast magnetic resonance imaging (MRI) assessed response and primary tumour pathology factors could identify a subset of patients that might be spared axillary node clearance. METHODS: A retrospective data analysis was performed of patients with core biopsy-proven axillary nodal metastasis prior to commencement of neoadjuvant chemotherapy (NAC) who had subsequent axillary node clearance (ANC) at definitive breast surgery. Breast tumour and axillary response at MRI before, during and on completion of NAC, core biopsy tumour grade, tumour type and immunophenotype were correlated with pathological response in the breast and the number of metastatic nodes in the ANC specimens. RESULTS: Of 87 consecutive patients with MRI at baseline, interim and after neoadjuvant chemotherapy who underwent ANC at time of breast surgery, 33 (38%) had no residual macrometastatic axillary disease, 28 (32%) had 1-2 metastatic nodes and 26 (30%) had more than 2 metastatic nodes. Factors that predicted axillary nodal complete response were MRI complete response in the breast (p < 0.0001), HER2 positivity (p = 0.02) and non-lobular tumour type (p = 0.015). CONCLUSION: MRI assessment of breast tumour response to NAC and core biopsy factors are predictive of response in axillary nodes, and can be used to guide decision making regarding appropriate axillary surgery.


Asunto(s)
Neoplasias de la Mama/diagnóstico por imagen , Metástasis Linfática/diagnóstico por imagen , Imagen por Resonancia Magnética/normas , Adulto , Anciano , Antineoplásicos/uso terapéutico , Axila/diagnóstico por imagen , Axila/patología , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/patología , Femenino , Humanos , Ganglios Linfáticos/diagnóstico por imagen , Ganglios Linfáticos/patología , Metástasis Linfática/tratamiento farmacológico , Metástasis Linfática/patología , Persona de Mediana Edad , Terapia Neoadyuvante
16.
Langmuir ; 35(44): 14310-14315, 2019 Nov 05.
Artículo en Inglés | MEDLINE | ID: mdl-31647673

RESUMEN

The interfacial spreading and exfoliation of graphene was used to create low-density, hollow microspheres defined by a thin shell of graphene. The spheres were templated by a thermodynamically driven self-assembly process in which graphite spontaneously exfoliated and spread at the high-energy interfaces of a water-in-oil emulsion. Graphene thus acted as a 2D surfactant to stabilize the dispersed water droplets utilized as polymerization templates. Using a mixture of organic solvent and monomer as the emulsion oil phase, polystyrene-coated hollow graphene microspheres were created. These spheres were characterized by optical and electron microscopy, thermo-gravimetric analysis, nanoindentation, and particle sizing. The mechanism leading to the microsphere surface morphology and shape is discussed, with the oil phase composition shown to play a critical role.

17.
ACS Appl Mater Interfaces ; 11(35): 32339-32345, 2019 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-31408317

RESUMEN

Highly conductive, metal-like poly(ethylene terephthalate) (PET) nonwoven fabric was prepared by coating poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) containing dimethyl sulfoxide (DMSO) onto PET nonwoven fabric previously coated with graphene/graphite. The sheet resistance of the original nonwoven fabric decreases from >80 MΩ□-1 to 1.1 Ω□-1 after coating with 10.7 wt % graphene and 5.48 wt % PEDOT:PSS with a maximum current at breakdown of 4 A. This sheet resistance is lower than previously reported sheet resistances of fabrics coated with graphene films, PEDOT:PSS films, or PEDOT:PSS coated fabrics from the literature. The effect of temperature on the resistance of graphene/PEDOT:PSS coated fabric has revealed that the resistance decreases with increasing temperature, analogous to semiconductors, with a clear semiconductor-metal transition occurring at 290 K. Finally, a coating of 18 wt % graphene/graphite and 2.5 wt % PEDOT:PSS (Rs = 5.5 Ω□-1) screen printed on the nonwoven fabric was shown to function as an electrode for electrocardiography without any hydrogel and with dry skin conditions. This composite coating finds application in wearable electronics for military and consumer sectors.


Asunto(s)
Compuestos Bicíclicos Heterocíclicos con Puentes , Electrocardiografía , Polímeros , Textiles , Adulto , Electrodos , Humanos , Masculino
18.
Nanoscale ; 10(30): 14441-14447, 2018 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-29726576

RESUMEN

We describe a method using simple optical microscopy and image processing that simultaneously characterizes thousands of nanosheets in a sample area on the order of 1 mm2. Including data acquisition and processing, both the number of atomic layers and the lateral sizes of all sheets can be obtained within a few hours-approximately 100 times faster than with previous methods, such as atomic force microscopy. This is achieved by normalizing the optical image based on substrate brightness, which eliminates inhomogeneities usually limiting optical techniques. Ultimately, the method enables robust statistical analysis of populations of nanosheet materials. We demonstrate the utility of this method by examining fractions made from a sample of graphene oxide (GO) made using an emulsion-based method. Beyond providing the morphological composition of the samples, the reported method is sensitive enough to provide information about the oxidation level of a population of GO sheets and, correspondingly, optical constants of the material.

19.
J Clin Oncol ; 36(19): 1981-1990, 2018 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-29718793

RESUMEN

Purpose The role of temporary ovarian suppression with gonadotropin-releasing hormone agonists (GnRHa) during chemotherapy as a strategy to preserve ovarian function and fertility in premenopausal women remains controversial. This systematic review and meta-analysis using individual patient-level data was conducted to better assess the efficacy and safety of this strategy in patients with early breast cancer. Methods The trials in which premenopausal women with early breast cancer were randomly assigned to receive (neo)adjuvant chemotherapy alone or with concurrent GnRHa were eligible for inclusion. Primary end points were premature ovarian insufficiency (POI) rate and post-treatment pregnancy rate. Disease-free survival and overall survival were secondary end points. Because each study represents a cluster, statistical analyses were performed using a random effects model. Results A total of 873 patients from five trials were included. POI rate was 14.1% in the GnRHa group and 30.9% in the control group (adjusted odds ratio, 0.38; 95% CI, 0.26 to 0.57; P < .001). A total of 37 (10.3%) patients had at least one post-treatment pregnancy in the GnRHa group and 20 (5.5%) in the control group (incidence rate ratio, 1.83; 95% CI, 1.06 to 3.15; P = .030). No significant differences in disease-free survival (adjusted hazard ratio, 1.01; 95% CI, 0.72 to 1.42; P = .999) and overall survival (adjusted hazard ratio, 0.67; 95% CI, 0.42 to 1.06; P = .083) were observed between groups. Conclusion Our findings provide evidence for the efficacy and safety of temporary ovarian suppression with GnRHa during chemotherapy as an available option to reduce the likelihood of chemotherapy-induced POI and potentially improve future fertility in premenopausal patients with early breast cancer.


Asunto(s)
Neoplasias de la Mama/tratamiento farmacológico , Preservación de la Fertilidad/métodos , Hormona Liberadora de Gonadotropina/agonistas , Tratamientos Conservadores del Órgano/métodos , Ovario/efectos de los fármacos , Insuficiencia Ovárica Primaria/prevención & control , Adulto , Supervivencia sin Enfermedad , Femenino , Humanos , Premenopausia , Insuficiencia Ovárica Primaria/inducido químicamente , Ensayos Clínicos Controlados Aleatorios como Asunto , Resultado del Tratamiento
20.
J Biomed Opt ; 22(9): 1-11, 2017 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-28925107

RESUMEN

Indocyanine green (ICG), a Food and Drug Administration (FDA)-approved fluorophore with excitation and emission wavelengths inside the "optical imaging window," has been incorporated into nanocarriers (NCs) to achieve enhanced circulation time, targeting, and real-time tracking in vivo. While previous studies transferred ICG exogenously into NCs, here, a one-step rapid precipitation process [flash nanoprecipitation (FNP)] creates ICG-loaded NCs with tunable, narrow size distributions from 30 to 180 nm. A hydrophobic ion pair of ICG-tetraoctylammonium or tetradodecylammonium chloride is formed either in situ during FNP or preformed then introduced into the FNP feed stream. The NCs are formulated with cores comprising either vitamin E (VE) or polystyrene (PS). ICG core loadings of 30 wt. % for VE and 10 wt. % for PS are achieved. However, due to a combination of molecular aggregation and Förster quenching, maximum fluorescence (FL) occurs at 10 wt. % core loading. The FL-per-particle scales with core diameter to the third power, showing that FNP enables uniform volume encapsulation. By varying the ICG counter-ion ratio, encapsulation efficiencies above 80% are achieved even in the absence of ion pairing, which rises to 100% with 1∶1 ion pairing. Finally, while ICG ion pairs are shown to be stable in buffer, they partition out of NC cores in under 30 min in the presence of physiological albumin concentrations.


Asunto(s)
Colorantes Fluorescentes , Verde de Indocianina , Nanocápsulas , Interacciones Hidrofóbicas e Hidrofílicas , Tamaño de la Partícula
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA