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OBJECTIVE: MYCN oncogene amplification is closely linked to high-grade neuroblastoma with poor prognosis. Accurate quantification is essential for risk assessment, which guides clinical decision making and disease management. This study proposes an end-to-end deep-learning framework for automatic tumor segmentation of pediatric neuroblastomas and radiomics features-based classification of MYCN gene amplification. METHODS: Data from pretreatment contrast-enhanced computed tomography scans and MYCN status from 47 cases of pediatric neuroblastomas treated at a tertiary children's hospital from 2009 to 2020 were reviewed. Automated tumor segmentation and grading pipeline includes (1) a modified U-Net for tumor segmentation; (2) extraction of radiomic textural features; (3) feature-based ComBat harmonization for removal of variabilities across scanners; (4) feature selection using 2 approaches, namely, ( a ) an ensemble approach and ( b ) stepwise forward-and-backward selection method using logistic regression classifier; and (5) radiomics features-based classification of MYCN gene amplification using machine learning classifiers. RESULTS: Median train/test Dice score for modified U-Net was 0.728/0.680. The top 3 features from the ensemble approach were neighborhood gray-tone difference matrix (NGTDM) busyness, NGTDM strength, and gray-level run-length matrix (GLRLM) low gray-level run emphasis, whereas those from the stepwise approach were GLRLM low gray-level run emphasis, GLRLM high gray-level run emphasis, and NGTDM coarseness. The top-performing tumor classification algorithm achieved a weighted F1 score of 97%, an area under the receiver operating characteristic curve of 96.9%, an accuracy of 96.97%, and a negative predictive value of 100%. Harmonization-based tumor classification improved the accuracy by 2% to 3% for all classifiers. CONCLUSION: The proposed end-to-end framework achieved high accuracy for MYCN gene amplification status classification.
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Aprendizado Profundo , Neuroblastoma , Humanos , Criança , Proteína Proto-Oncogênica N-Myc/genética , Amplificação de Genes , Neuroblastoma/diagnóstico por imagem , Neuroblastoma/genética , Tomografia Computadorizada por Raios XRESUMO
This study aimed to improve the quality of 90Y PET imaging by optimizing the reconstruction algorithm. Methods: We recruited 10 patients with neuroendocrine tumor metastatic to the liver or primary hepatocellular carcinoma who were qualified for 90Y-labeled selective internal radiation therapy or peptide receptor radionuclide therapy. They underwent posttherapeutic PET/CT imaging using 3 different reconstruction parameters: VUE Point HD with a 6.4-mm filter cutoff, 24 subsets, and 2 iterations (algorithm A); VUE Point FX with a 6.0-mm filter cutoff, 18 subsets, and 3 iterations using time of flight (algorithm B); and VUE Point HD (LKYG) with a 5-mm filter cutoff, 32 subsets, and 1 iteration (algorithm C). The reconstructed PET/CT images were assessed by 10 nuclear medicine physicians using 4-point semiqualitative scoring criteria. A P value of less than 0.05 was considered significant. Results: The median quality assessment scores for algorithm C were consistently scored the highest, with algorithms A, B, and C, scoring 3, 2, and 4, respectively. The 90Y PET scans using algorithm C were deemed diagnostic 91% of the time. There was a statistically significant difference in quality assessment scores among the algorithms by the Kruskal-Wallis rank sum test ([Formula: see text] = 86.5, P < 0.001), with a mean rank quality score of 130.03 for algorithm A, 109.76 for algorithm B, and 211.71 for algorithm C. Subgroup analysis for quality assessment scoring of post-peptide receptor radionuclide therapy imaging alone showed a statistically significant difference between different scanning algorithms ([Formula: see text] = 35.35, P < 0.001), with mean rank quality scores of 45.85 for algorithm A, 50.05 for algorithm B, and 85.6 for algorithm C. Similar results were observed for quality assessment scoring of imaging after selective internal radiation therapy ([Formula: see text] = 79.90, P < 0.001), with mean ranks of 82.33 for algorithm A, 55.79 for algorithm B, and 133.38 for algorithm C. Conclusion: The new LKYG algorithm that was featured by decreasing the number of iterations, decreasing the cutoff of the filter thickness, and increasing the number of subsets successfully improved image quality.
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Carcinoma Hepatocelular , Neoplasias Hepáticas , Humanos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Imagens de Fantasmas , Tomografia por Emissão de Pósitrons/métodos , Algoritmos , Receptores de Peptídeos , Radioisótopos , Processamento de Imagem Assistida por Computador/métodosRESUMO
Introduction: With the rise in Caesarean deliveries, complications related to the procedure are increasingly encountered. Sonography has an indispensable role in the assessment of these complications and is often the first-line investigation of choice.Topic description: Part 2 of this pictorial review summarises the non-pregnant and pregnancy-related complications of Caesarean deliveries. Discussion: Non-pregnant complications include Caesarean scar defects, scar endometriosis and malpositioned intrauterine devices. Complications related to future gestations include scar ectopic pregnancy, abnormal placentation and intrapartum uterine dehiscence or rupture. Key sonographic features of these conditions are illustrated. Pitfalls, mimics, limitations and indications for cross-sectional imaging are discussed. Conclusion: Sound knowledge of the sonographic features of common non-pregnant and pregnancy-related complications of Caesarean delivery will facilitate accurate diagnosis, timely management and improved patient outcomes.
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Introduction: With the rise in Caesarean deliveries, complications related to the procedure are increasingly encountered. Sonography has an indispensable role in the assessment of these complications and is often the first-line investigation of choice.Topic Description: Part 1 of this pictorial review summarises the early complications unique to and associated with Caesarean deliveries. Discussion: Acute haemorrhagic complications include retained products of conception, subfascial and bladder flap haematomas and, rarely, postpartum uterine dehiscence or rupture and iatrogenic vascular complications. Infective complications include puerperal and wound infections. Key sonographic features of these conditions are illustrated. Pitfalls, mimics, limitations and indications for cross-sectional imaging are discussed. Conclusion: Sound knowledge of the sonographic features of common early complications of Caesarean delivery will facilitate accurate diagnosis, timely management and improved patient outcomes.
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Functional biointerfaces hold broad significance for designing cell-responsive medical implants and sensor devices. Solid-supported phospholipid bilayers are a promising class of biological materials to build bioinspired thin-film coatings, as they can facilitate interactions with cell membranes. However, it remains challenging to fabricate lipid bilayers on medically relevant materials such as titanium oxide surfaces. There are also limitations in existing bilayer printing capabilities since most approaches are restricted to either deposition alone or to fixed microarray patterning. By combining advances in lipid surface chemistry and on-demand inkjet printing, we demonstrate the direct deposition and patterning of covalently tethered lipid bilayer membranes on titanium oxide surfaces, in ambient conditions and without any surface pretreatment process. The deposition conditions were evaluated by quartz crystal microbalance-dissipation (QCM-D) measurements, with corresponding resonance frequency (Δf) and energy dissipation (ΔD) shifts of around −25 Hz and <1 × 10−6, respectively, that indicated successful bilayer printing. The resulting printed phospholipid bilayers are stable in air and do not collapse following dehydration; through rehydration, the bilayers regain their functional properties, such as lateral mobility (>1 µm2/s diffusion coefficient), according to fluorescence recovery after photobleaching (FRAP) measurements. By taking advantage of the lipid bilayer patterned architectures and the unique features of titanium oxide's photoactivity, we further show how patterned cell culture arrays can be fabricated. Looking forward, this work presents new capabilities to achieve stable lipid bilayer patterns that can potentially be translated into implantable biomedical devices.
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PURPOSE: MYCN onco-gene amplification in neuroblastoma confers patients to the high-risk disease category for which prognosis is poor and more aggressive multimodal treatment is indicated. This retrospective study leverages machine learning techniques to develop a computed tomography (CT)-based model incorporating semantic and non-semantic features for non-invasive prediction of MYCN amplification status in pediatric neuroblastoma. METHODS: From 2009 to 2020, 54 pediatric patients treated for neuroblastoma at a specialized children's hospital with pre-treatment contrast-enhanced CT and MYCN status were identified (training cohort, n = 44; testing cohort, n = 10). Six morphologic features and 107 quantitative gray-level texture radiomics features extracted from manually drawn volume-of-interest were analyzed. Following feature selection and class balancing, the final predictive model was developed with eXtreme Gradient Boosting (XGBoost) algorithm. Accumulated local effects (ALE) plots were used to explore main effects of the predictive features. Tumor texture maps were also generated for visualization of radiomics features. RESULTS: One morphologic and 2 radiomics features were selected for model building. The XGBoost model from the training cohort yielded an area under the receiver operating characteristics curve (AUC-ROC) of 0.930 (95% CI, 0.85-1.00), optimized F1-score of 0.878, and Matthews correlation coefficient (MCC) of 0.773. Evaluation on the testing cohort returned AUC-ROC of 0.880 (95% CI, 0.64-1.00), optimized F1-score of 0.933, and MCC of 0.764. ALE plots and texture maps showed higher "GreyLevelNonUniformity" values, lower "Strength" values, and higher number of image-defined risk factors contribute to higher predicted probability of MYCN amplification. CONCLUSION: The machine learning model reliably classified MYCN amplification in pediatric neuroblastoma and shows potential as a surrogate imaging biomarker.
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Amplificação de Genes , Neuroblastoma , Criança , Humanos , Proteína Proto-Oncogênica N-Myc/genética , Neuroblastoma/diagnóstico por imagem , Neuroblastoma/genética , Estudos Retrospectivos , Tomografia Computadorizada por Raios X/métodosRESUMO
Amongst medical undergraduates, the perception of educational environment (EE) has been associated with academic achievement and positive attitude toward the course. Nonetheless, there are sparse data on how it influences various learning processes and outcomes especially within psychiatry training. Consistent with situativity and self-determination learning theories, we hypothesized that a positive perception of the EE within psychiatry postings will be beneficial for the learning process, specifically pertaining to greater motivation to learn, better engagement, allowing them to feel more equipped, and greater appreciation of the subject. The DREEM (Dundee Ready Education Environment Measure) was administered to fourth-year medical undergraduate students from the Yong Loo Lin School of Medicine, Singapore, undergoing psychiatry rotations from 2015 to 2019. The students also completed five additional items evaluating the specific learning processes (motivation to learn, engagement, equipping, and appreciation of the subject) and overall rating of the posting. We examined the relationship between DREEM domains and learning processes using correlation analysis. We explored learning processes as mediators of the relationship between total DREEM scores and overall rating of the posting. Altogether, 1343 (response rate 89.5%) medical undergraduates participated in the study. The overall DREEM score was 157.01 ± 15.86. Overall DREEM and subdomain scores were significantly correlated with several learning processes (r = 0.354 to 0.558, all p < .001). Motivation and engagement were significant mediators of the relationship between total DREEM scores and overall rating of the psychiatry posting. Our results highlighted that a positive perception of EE was associated with the specific learning processes that mediated the overall rating of the posting. In the context of relevant learning theories and our study findings, improvement of the EE within undergraduate psychiatry training can potentially enhance overall learning experience through better motivation and engagement of our learners.
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Educação de Graduação em Medicina , Psiquiatria , Estudantes de Medicina , Humanos , Percepção , Inquéritos e QuestionáriosRESUMO
OBJECTIVE: To perform an individual patient data level meta-analysis of randomised controlled trials comparing drug coated balloon angioplasty (DCB) against conventional percutaneous transluminal angioplasty (PTA) in the treatment of dysfunctional haemodialysis venous access. METHODS: A search was conducted from inception to 13 November 2020. Kaplan-Meier curves comparing DCB with PTA by target lesion primary patency (TLPP) and access circuit primary patency (ACPP) were graphically reconstructed to retrieve patient level data. One stage meta-analyses with Cox models with random effects shared frailties were conducted to determine hazard ratios (HRs). Dynamic restricted mean survival times (RMST) were conducted in view of violation of the proportional hazards assumption. Conventional two stage meta-analyses and network meta-analyses under random effects Frequentist models were conducted to determine overall and comparative outcomes of paclitaxel concentrations used. Where outliers were consistently detected through outlier and influence analyses, sensitivity analyses excluding those studies were conducted. RESULTS: Among 10 RCTs (1 207 patients), HRs across all models favoured DCB (one stage shared frailty HR 0.62, 95% CI 0.53 - 0.73, p < .001; two stage random effects HR 0.60, 95% CI 0.42 - 0.86, p = .018, I2 = 65%) for TLPP. Evidence of time varying effects (p = .005) was found. TLPP RMST was + 3.54 months (25.0%) longer in DCB treated patients compared with PTA (p = .001) at three years. TLPP at six months, one year, and two years was 75.3% vs. 58.1%, 51.1% vs. 37.1%, and 31.4% vs. 26.0% for DCB and PTA, respectively. The P-Scores within the Frequentist network meta-analysis suggest that higher concentrations of paclitaxel were associated with better TLPP and ACPP. Among six RCTs (854 patients), the one stage model favoured DCB (shared frailty HR 0.72, 95% CI 0.60 - 0.87, p < .001) for ACPP. Conversely, the two stage random effects model demonstrated no significant difference (HR 0.76, 95% CI 0.35 - 1.67, p = .41, I2 = 81%). Sensitivity analysis excluding outliers significantly favoured DCB (HR 0.61, 95% CI 0.41 - 0.91, p = .027, I2 = 62%). CONCLUSION: Overall evidence suggests that DCB is favoured over PTA in TLPP and ACPP.
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Angioplastia com Balão/instrumentação , Derivação Arteriovenosa Cirúrgica/efeitos adversos , Fármacos Cardiovasculares/administração & dosagem , Materiais Revestidos Biocompatíveis , Oclusão de Enxerto Vascular/terapia , Diálise Renal , Dispositivos de Acesso Vascular , Adulto , Idoso , Idoso de 80 Anos ou mais , Angioplastia com Balão/efeitos adversos , Fármacos Cardiovasculares/efeitos adversos , Feminino , Oclusão de Enxerto Vascular/etiologia , Oclusão de Enxerto Vascular/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Ensaios Clínicos Controlados Aleatórios como Assunto , Medição de Risco , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento , Grau de Desobstrução VascularRESUMO
PURPOSE: To evaluate the efficacy of hepatic arterial infusion (HAI), conventional transarterial chemoembolization, drug-eluting embolic transarterial chemoembolization (DEE-TACE), transarterial radioembolization, and their combinations with systemic chemotherapy (SCT) for unresectable colorectal liver metastases. METHODS: A search was conducted on Embase, Scopus, PubMed, and Web of Science for prospective nonrandomized studies and randomized controlled trials (RCTs) from inception to June 20, 2020. Survival data of patients were recovered from original Kaplan-Meier curves by exploiting a graphical reconstructive algorithm. One-stage meta-analyses were conducted for the median overall survival (OS), survival rates (SRs), and restricted mean survival time (RMST), whereas two-stage meta-analyses of proportions were conducted to determine response rates (RRs) and conversion to resection rates (CRRs). RESULTS: A total of 71 prospective nonrandomized studies and 21 RCTs were identified, comprising 6,695 patients. Among patients treated beyond the first-line, DEE-TACE + SCT (n = 152) had the best survival outcomes of median OS of 26.5 (95% confidence interval [CI], 22.5-29.1) months and a 3-year RMST of 23.6 (95% CI, 21.8-25.5) months. Upon further stratification by publication year, DEE-TACE + SCT appeared to consistently have the highest pooled SRs at 1 year (81.9%) and 2 years (66.1%) in recent publications (2015-2020). DEE-TACE + SCT and HAI + SCT had the highest pooled RRs of 56.7% (I2 = 0.90) and 62.6% (I2 = 0.87) and pooled CRRs of 35.5% (I2 = 0.00) and 30.3% (I2 = 0.80), respectively. CONCLUSIONS: Albeit significant heterogeneity, the paucity of high-quality evidence, and the noncomparative nature of all analyses, the overall evidence suggests that patients treated with DEE-TACE + SCT have the best oncological outcomes and greatest potential to be converted for resection.
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Braquiterapia , Carcinoma Hepatocelular , Quimioembolização Terapêutica , Neoplasias Colorretais , Embolização Terapêutica , Neoplasias Hepáticas , Carcinoma Hepatocelular/terapia , Quimioembolização Terapêutica/efeitos adversos , Neoplasias Colorretais/terapia , Embolização Terapêutica/efeitos adversos , Humanos , Neoplasias Hepáticas/terapia , Taxa de Sobrevida , Resultado do TratamentoRESUMO
Intrauterine fetal demise (IUFD) is an uncommon but serious event that may occasionally be encountered on fetal MRI. Compared to the more florid signs of fetal demise which has occurred some time ago, recent IUFD is associated with more subtle findings that may be missed or misinterpreted. The two main MRI sequences used in imaging the fetus are T2-like two-dimensional balanced steady-state free-precession (SSFP), a white blood sequence, or T2-weighted single-shot fast spin-echo (SSFSE), a black blood sequence. The most reliable and specific signs of a recent IUFD are a constricted heart with poorly delineated cardiac chambers and signal abnormality in the heart and aorta, which will have different features depending on the MRI sequence used. Secondary signs of IUFD include global brain ischemia, abnormal globes, effusions, body wall edema and umbilical cord thrombosis. Unlike fetal ultrasound examinations where cardiac activity is routinely assessed, fetal MRI requires careful scrutiny of the fetal heart for assessment of fetal life.
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Morte Fetal , Imageamento por Ressonância Magnética , Edema , Feminino , Humanos , Gravidez , Ultrassonografia Pré-NatalRESUMO
The Singapore Health Services cluster (SingHealth) radiology film archives are a valuable repository of local radiological cases dating back to the 1950s. Some of the cases in the archives are of historical medical interest, i.e. cerebral angiography in the workup of patients with hemiplegia. Other cases are of historical social interest, being conditions seen during earlier stages of Singapore's development, i.e. bound feet. The archives form a unique portal into the development of local radiology as well as the national development of Singapore. A selection from the archives is published in commemoration of the International Day of Radiology in 2020, as well as the 200th anniversary of the Singapore General Hospital in 2021. This pictorial essay comprises gastroenterology, musculoskeletal and obstetrics and gynaecology cases from the archives.
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Gastroenterologia , Ginecologia , Obstetrícia , Radiologia , Humanos , SingapuraRESUMO
The Singapore Health Services cluster (SingHealth) radiology film archives are a valuable repository of local radiological cases dating back to the 1950s. Some of the cases in the archives are of historical medical interest, i.e. cerebral angiography in the workup of patients with hemiplegia. Other cases are of historical social interest, being conditions seen during earlier stages of Singapore's development, i.e. bound feet. The archives form a unique portal into the development of local radiology as well as the national development of Singapore. A selection from the archives is published in 2020 in commemoration of the 20th anniversary of the formation of SingHealth, the 55th National Day of Singapore, and the 125th anniversary of the International Day of Radiology. This pictorial essay comprises cardiovascular, respiratory and neurological cases from the archives.
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Radiologia , Humanos , SingapuraRESUMO
Sporoderms, the outer layers of plant spores and pollen grains, are some of the most robust biomaterials in nature. In order to evaluate the potential of sporoderms in biomedical applications, we studied the biodegradation in simulated gastrointestinal fluid of sporoderm microcapsules (SDMCs) derived from four different plant species: lycopodium (Lycopodium clavatum L.), camellia (Camellia sinensis L.), cattail (Typha angustifolia L.), and dandelion (Taraxacum officinale L.). Dynamic image particle analysis (DIPA) and field-emission scanning electron microscopy (FE-SEM) were used to investigate the morphological characteristics of the capsules, and Fourier-transform infrared (FTIR) spectroscopy was used to evaluate their chemical properties. We found that SDMCs undergo bulk degradation in a species-dependent manner, with camellia SDMCs undergoing the most extensive degradation, and dandelion and lycopodium SDMCs being the most robust.
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Biodegradação Ambiental , Biopolímeros/química , Cápsulas/química , Carotenoides/química , Materiais Biocompatíveis , Pólen/química , Análise Espectral , Esporos/químicaRESUMO
Plant sporoderm are among the most robust biomaterials in nature. We investigate the erosion of Lycopodium sporoderm microcapsules (SDMCs) triggered by human blood plasma. Dynamic image particle analysis (DIPA), field emission scanning electron microscopy (FESEM) and Fourier transform infrared (FTIR) spectroscopy demonstrate the degradation events, suggesting bulk erosion as the dominant mechanism for SDMCs fragmentation in human blood. These results should prove valuable in discerning the behaviour of SDMCs in potential biological applications.
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Implantes Absorvíveis , Materiais Biocompatíveis/química , Cápsulas/química , Lycopodium/química , Plasma/química , Humanos , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Pine pollen offers an all-natural multicavity structure with dual hollow air sacs, providing ample cargo capacity available for compound loading. However, the pollen exhibits reduced permeability because of the presence of a thin natural water-proofing layer of lipidic compounds. Herein, we explore the potential for compound loading within pine pollen and the potential for developing all-natural formulations for targeted delivery to the intestinal tract. Removal of the surface-adhered lipidic compounds is shown to improve surface wetting, expose nanochannel structures in the outer pollen shell and enhance water uptake throughout the whole pollen structure. Optimization of loading parameters enabled effective compound loading within the outer pollen shell sexine structure, with bovine serum albumin (BSA) serving as a representative protein. All-natural oral delivery formulations for targeted intestinal delivery are developed based on tableting of BSA-loaded defatted pine pollen, with the incorporation of xanthan gum as a natural binder, or ionotropically cross-linked sodium alginate as an enteric coating. Looking forward, the large cargo capacity, ease of compound loading, competitive cost, abundant availability, and extensive historical usage as food and medicine make pine pollen an attractive microencapsulant for a wide range of potential applications.
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Substâncias Macromoleculares/química , Animais , Preparações de Ação Retardada , Composição de Medicamentos , Pólen , Soroalbumina BovinaRESUMO
Pollen-based microcapsules such as hollow sporopollenin exine capsules (SECs) have emerged as excellent drug delivery and microencapsulation vehicles. To date, SECs have been extracted primarily from a wide range of natural pollen species possessing largely spherical geometries and uniform surface features. Nonetheless, exploring pollen species with more diverse architectural features could lead to new application possibilities. One promising class of candidates is dandelion pollen grains, which possess architecturally intricate, cage-like microstructures composed of robust sporopollenin biopolymers. Here, we report the successful extraction and macromolecular loading of dandelion SECs. Preservation of SEC morphology and successful removal of proteinaceous materials was evaluated using scanning electron microscopy (SEM), matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry, elemental CHN analysis, dynamic image particle analysis (DIPA) and confocal laser scanning microscopy (CLSM). Among the tested processing schemes, acidolysis using 85% (v/v) phosphoric acid refluxed at 70 °C for 5 hours yielded an optimal balance of intact particle yield, protein removal, and preservation of cage-like microstructure. For proof-of-concept loading, bovine serum albumin (BSA) was encapsulated within the dandelion SECs with high efficiency (32.23 ± 0.33%). Overall, our findings highlight how hollow microcapsules with diverse architectural features can be readily prepared and utilized from plant-based materials.
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Biopolímeros , Carotenoides , Pólen , Cápsulas , Composição de Medicamentos , Sistemas de Liberação de Medicamentos , Espectrometria de Massas , Microscopia Confocal , Microscopia Eletrônica de Varredura , Pólen/química , Pólen/ultraestrutura , TaraxacumRESUMO
The structural features of biological organisms have evolved through natural selection to provide highly tailored functions, inspiring numerous biomimetic and biological design strategies. A wide scope of untapped potential lies in harnessing the nanoscale architectural properties of natural biological materials to develop high-performance sensors. Herein, we report the development of an ultrasensitive chemical sensor that is based on the three-dimensional (3D) biomimetic templating of a structurally hierarchical butterfly wing. In conjunction with graphene sheet coating strategies, the porous 3D architecture enables highly selective detection of diabetes-related volatile organic compounds (VOCs), including a rapid response time (≤1 s), a low limit of detection (20 ppb), and superior mechanical properties. Taken together, the findings in this work demonstrate the promise of incorporating natural biological materials into high-performance sensors, with excellent potential for wearable and flexible sensors.
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Microcapsules derived from plant-based spores or pollen provide a robust platform for a diverse range of microencapsulation applications. Sporopollenin exine capsules (SECs) are obtained when spores or pollen are processed so as to remove the internal sporoplasmic contents. The resulting hollow microcapsules exhibit a high degree of micromeritic uniformity and retain intricate microstructural features related to the particular plant species. Herein, we demonstrate a streamlined process for the production of SECs from Lycopodium clavatum spores and for the loading of hydrophilic compounds into these SECs. The current SEC isolation procedure has been recently optimized to significantly reduce the processing requirements which are conventionally used in SEC isolation, and to ensure the production of intact microcapsules. Natural L. clavatum spores are defatted with acetone, treated with phosphoric acid, and extensively washed to remove sporoplasmic contents. After acetone defatting, a single processing step using 85% phosphoric acid has been shown to remove all sporoplasmic contents. By limiting the acid processing time to 30 hr, it is possible to isolate clean SECs and avoid SEC fracturing, which has been shown to occur with prolonged processing time. Extensive washing with water, dilute acids, dilute bases, and solvents ensures that all sporoplasmic material and chemical residues are adequately removed. The vacuum loading technique is utilized to load a model protein (Bovine Serum Albumin) as a representative hydrophilic compound. Vacuum loading provides a simple technique to load various compounds without the need for harsh solvents or undesirable chemicals which are often required in other microencapsulation protocols. Based on these isolation and loading protocols, SECs provide a promising material for use in a diverse range of microencapsulation applications, such as, therapeutics, foods, cosmetics, and personal care products.
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Cápsulas , Composição de Medicamentos , Pólen , Biopolímeros , Carotenoides , SolventesRESUMO
BACKGROUND: Studies on the effects of cement augmentation or vertebroplasty on multi-level spine after vertebral compression fractures are lacking. This paper seeks to establish a 3-vertebrae ovine model to determine the impact of compression fracture on spine biomechanics, and to discover if cement augmentation can restore mechanical stability to fractured spine. METHODS: Five lumbar spine segments (L1-L3) were obtained from 5-year-old female Merino sheep. Standardized wedge-compression fractures were generated in each L2 vertebra, and then augmented with polymethyl methacrylate (PMMA) cement mixed with 30% barium sulphate powder. Biomechanical pure moment testing in axial rotation (AR), flexion/extension (FE) and lateral bending (LB) was carried out in the intact, fractured and repaired states. Range of motion (ROM) and neutral zone (NZ) parameters were compared, and plain radiographs taken at every stage. RESULTS: Except for a significant increase in ROM between the intact and fractured states in AR between L1 and L2 (P<0.05), there were no other significant differences in ROM or NZ between the other groups. There was a trend towards an increase in ROM and NZ in all directions after fracture, but this did not reach significance. Normal biomechanics was only minimally restored after augmentation. CONCLUSIONS: Results suggest that cement augmentation could not restore mechanical stability of fractured spine. Model-specific factors may have had a role in these findings. Caution should be exercised when applying these results to humans.
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Sporopollenin exine capsules (SECs) extracted from Lycopodium clavatum spores are an attractive biomaterial possessing a highly robust structure suitable for microencapsulation strategies. Despite several decades of research into SEC extraction methods, the protocols commonly used for L. clavatum still entail processing with both alkaline and acidolysis steps at temperatures up to 180 °C and lasting up to 7 days. Herein, we demonstrate a significantly streamlined processing regimen, which indicates that much lower temperatures and processing durations can be used without alkaline lysis. By employing CHN elemental analysis, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and dynamic image particle analysis (DIPA), the optimum conditions for L. clavatum SEC processing were determined to include 30 hours acidolysis at 70 °C without alkaline lysis. Extending these findings to proof-of-concept encapsulation studies, we further demonstrate that our SECs are able to achieve a loading of 0.170 ± 0.01 g BSA per 1 g SECs by vacuum-assisted loading. Taken together, our streamlined processing method and corresponding characterization of SECs provides important insights for the development of applications including drug delivery, cosmetics, personal care products, and foods.