Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 70
Filtrar
1.
Macromol Rapid Commun ; : e2400098, 2024 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-38862122

RESUMEN

Cellulose nanopaper is a material structure that possesses high mechanical performance and is widely regarded as a promising 2D reinforcement for polymer matrix composites. This work explores the use of low grammage bacterial cellulose (BC) nanopaper as reinforcement for poly(acrylated urethane) interlayer adhesive to increase the impact performance of multilayer acrylic composites. The BC nanopaper is impregnated with an acrylated urethane resin and laminated between acrylic sheets to create BC/acrylic composites consisting of one, three, and five layers of BC nanopaper-reinforced poly(acrylated urethane) interlayer adhesive(s). Both the poly(acrylated urethane)-filled BC nanopaper interlayer adhesive and the resulting laminated acrylic composites are optically transparent. The incorporation of BC nanopaper into the poly(acrylated urethane) interlayer adhesive improves the tensile modulus by eightfold and the single-edge notched fracture toughness by 60% compared to neat poly(acrylated urethane). It is also found that using poly(acrylated urethane)-filled BC nanopaper interlayer adhesive proves beneficial to the impact properties of the resulting laminated acrylic composites. In Charpy impact testing, the impact strength of the multilayer acrylic composites increases by up to 130% compared to the "gold-standard" impact-modified monolithic acrylic, with a BC loading of only 1.6 wt%.

2.
ACS Appl Polym Mater ; 6(11): 6252-6261, 2024 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-38903398

RESUMEN

The processing of an immiscible polymer blend using melt blending (i.e., extrusion) often results in a polymer material with inferior mechanical performance compared with its virgin counterparts. Here, we report and compare the properties of immiscible polymer blends produced from industrial mixed plastic waste from shredder residue comprising at least four different polymers (acrylonitrile butadiene styrene, polystyrene, polypropylene, and polyethylene) with and without a prior melt-blending step employed. As anticipated, mixed plastic blend produced with a prior melt-blending step exhibited a more homogeneous microstructure, resulting in brittleness, poor work of fracture, and single-edge notched fracture toughness with a flat R-curve. Without the intimate polymers mixing arising from melt blending, the resulting mixed plastic blend was found to possess a more heterogeneous concentric ellipsoid microstructure with large single polymer domains. This mixed plastic blend demonstrated progressive failure under uniaxial tensile loading, along with a more ductile single-edge notched fracture toughness response accompanied by a growing R-curve. Digital image correlation and fractographic analysis revealed that melt blending created a large number of incompatible polymer boundaries that acted as stress concentration points, leading to brittleness and earlier onset catastrophic failure. The more heterogeneous mixed plastic blend produced without using a prior melt-blending step contains a smaller number of incompatible polymer boundaries. Additionally, the presence of larger single polymer domains also implies that the mechanical characteristics of the single polymer can be exploited in the immiscible mixed plastic blend. Our work opens up a simple pathway to add value to mixed plastic waste from shredder residue for use in engineering applications, diverting them away from landfill or incineration.

3.
Nat Biotechnol ; 2024 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-38565971

RESUMEN

Environmental concerns are driving interest in postpetroleum synthetic textiles produced from microbial and fungal sources. Bacterial cellulose (BC) is a promising sustainable leather alternative, on account of its material properties, low infrastructure needs and biodegradability. However, for alternative textiles like BC to be fully sustainable, alternative ways to dye textiles need to be developed alongside alternative production methods. To address this, we genetically engineer Komagataeibacter rhaeticus to create a bacterial strain that grows self-pigmenting BC. Melanin biosynthesis in the bacteria from recombinant tyrosinase expression achieves dark black coloration robust to material use. Melanated BC production can be scaled up for the construction of prototype fashion products, and we illustrate the potential of combining engineered self-pigmentation with tools from synthetic biology, through the optogenetic patterning of gene expression in cellulose-producing bacteria. With this study, we demonstrate that combining genetic engineering with current and future methods of textile biofabrication has the potential to create a new class of textiles.

5.
ACS Nano ; 17(10): 9049-9058, 2023 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-37171183

RESUMEN

The discovery of chiral spin texture has unveiled many unusual yet extraordinary physical phenomena, such as the Néel type domain walls and magnetic skyrmions. A recent theoretical study suggests that a chiral exchange interaction is not limited to a single ferromagnetic layer; instead, three-dimensional spin textures can arise from an interlayer Dzyaloshinskii-Moriya interaction. However, the influence of chiral interlayer exchange coupling on the electrical manipulation of magnetization has rarely been addressed. Here, the coexistence of both symmetric and chiral interlayer exchange coupling between two orthogonally magnetized CoFeB layers in PtMn/CoFeB/W/CoFeB/MgO is demonstrated. Images from polar magneto-optical Kerr effect microscopy indicate that the two types of coupling act concurrently to induce asymmetric domain wall propagation, where the velocities of domain walls with opposite chiralities are substantially different. Based on this microscopic mechanism, field-free switching of the perpendicularly magnetized CoFeB is achieved with a wide range of W thicknesses of 0.6-4.5 nm. This work enriches the understanding of interlayer exchange coupling for spintronic applications.

6.
Singapore Med J ; 2023 Apr 06.
Artículo en Inglés | MEDLINE | ID: mdl-37077051

RESUMEN

Introduction: Vaccination is critical in controlling the coronavirus disease 2019 (COVID-19) pandemic. However, vaccine perception and acceptance among pregnant and lactating women is unknown in Singapore. We aimed to determine the acceptance of COVID-19 vaccination among these two groups of women in Singapore and the factors associated with vaccine acceptance. Methods: We conducted an anonymous, online survey on the perceptions of the COVID-19 vaccine and its acceptance by pregnant and lactating women at a tertiary maternal and child hospital in Singapore from 1 March to 31 May 2021. Information on their demographics and knowledge was collected. These factors were assessed for their relationship with vaccine acceptance. Results: A total of 201 pregnant and 207 lactating women participated. Vaccine acceptance rates in pregnant and lactating women were 30.3% and 16.9%, respectively. Pregnant women who were unsure or unwilling to take the vaccine cited concerns about safety of the vaccine during pregnancy (92.9%), while lactating women were concerned about its potential long-term negative effects on the breastfeeding child (75.6%). Factors that were positively associated with vaccine acceptance included a lower monthly household income or education level, appropriate knowledge regarding vaccine mechanism and higher perceived maternal risk of COVID-19. Most pregnant (70.0%) and lactating women (83.7%) were willing to take the vaccine only when more safety data during pregnancy and breastfeeding were available. Conclusion: COVID-19 vaccine acceptance was low among pregnant and lactating women in Singapore. Addressing the safety concerns when more data are available and education on the mechanism of vaccine action will likely improve acceptance among these women.

7.
Women Health ; 63(3): 175-185, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36597593

RESUMEN

Developmental Origin of Health and Disease (DOHaD) explains how the health of the mother influences the offspring's risk of non-communicable diseases in later life. However, this remains underutilized in clinical practice. This study aimed to investigate the knowledge, attitude, and practice (KAP) of medical students, Obstetrics and Gynecology (O&G) and Pediatrics residents, toward DOHaD, identify potential barriers to DOHaD counseling, and translate DOHaD concepts into clinical practice. This cross-sectional study was conducted with a multi-section digital questionnaire, rated on a five-point Likert scale (1-5), with a higher score indicating better KAP. The scores between groups were compared using ANOVA. A total of 117 participants, comprising medical students (n = 75, 64.1 percent), O&G (n = 33, 28.2 percent) and Pediatric residents (n = 9, 7.7 percent), completed the questionnaire. The mean scores for the "Knowledge," "Attitude" and "Practice" sections were 3.73 (standard deviation 0.82), 4.27 (0.59) and 3.03 (0.52), respectively. O&G residents scored higher for the "Practice" section than Pediatric residents (mean scores 3.17 vs. 2.16; p = .048). Overall, the participants demonstrated good knowledge and attitude, but poor practice toward DOHaD. Thus, there is a need to improve education and training for health care professionals, develop a structured implementation framework, and provide a transdisciplinary care continuum for mother and child.


Asunto(s)
Ginecología , Obstetricia , Estudiantes de Medicina , Femenino , Embarazo , Humanos , Niño , Ginecología/educación , Estudiantes de Medicina/psicología , Estudios Transversales , Conocimientos, Actitudes y Práctica en Salud
8.
Vaccines (Basel) ; 10(8)2022 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-36016210

RESUMEN

Immune escape is observed with SARS-CoV-2 Omicron (Pango lineage B.1.1.529), the predominant circulating strain worldwide. A booster dose was shown to restore immunity against Omicron infection; however, real-world data comparing mRNA (BNT162b2; Comirnaty) and inactivated vaccines' (CoronaVac; Sinovac) homologous and heterologous boosting are lacking. A retrospective study was performed to compare the rate and outcome of COVID-19 in healthcare workers (HCWs) with various vaccination regimes during a territory-wide Omicron BA.2.2 outbreak in Hong Kong. During the study period from 1 February to 31 March 2022, 3167 HCWs were recruited, and 871 HCWs reported 746 and 183 episodes of significant household and non-household close contact. A total of 737 HCWs acquired COVID-19, all cases of which were all clinically mild. Time-dependent Cox regression showed that, compared with two-dose vaccination, three-dose vaccination reduced infection risk by 31.7% and 89.3% in household contact and non-household close contact, respectively. Using two-dose BNT162b2 as reference, two-dose CoronaVac recipient had significantly higher risk of being infected (HR 1.69 p < 0.0001). Three-dose BNT162b2 (HR 0.4778 p< 0.0001) and two-dose CoronaVac + BNT162b2 booster (HR 0.4862 p = 0.0157) were associated with a lower risk of infection. Three-dose CoronaVac and two-dose BNT162b2 + CoronaVac booster were not significantly different from two-dose BNT162b2. The mean time to achieve negative RT-PCR or E gene cycle threshold 31 or above was not affected by age, number of vaccine doses taken, vaccine type, and timing of the last dose. In summary, we have demonstrated a lower risk of breakthrough SARS-CoV-2 infection in HCWs given BNT162b2 as a booster after two doses of BNT162b2 or CoronaVac.

9.
Medicine (Baltimore) ; 101(27): e29859, 2022 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-35801739

RESUMEN

To assess the most influential factor for pupil diameter changes among age, illuminance, and refractive state and reestablish the optimal procedures for clinical applications based on refractive state and illuminance for different age groups. The study was an observational study (repeated measure study). Participants included 219 Korean adults aged 20 to 69 years. Pupil diameters were measured using a pupilometer under scotopic, mesopic-low, and mesopic-high lighting conditions. Factor interactions among age, illuminance, and refractive state were evaluated using mixed linear model and chi-square automated interaction detection. Illuminance mainly contributed to variations in pupil diameter of participants over 50 years, whereas the refractive state was the dominant controlling factor for the pupil variation in participants below 50 years. For more generalized application, the pupil diameter decreased with older age and brighter illuminance (P < .001, inverse correlation, all comparisons). The mean pupil diameter was significantly higher in myopes and emmetropes than in hyperopes (P < .001). Pupil diameter variation modeled using the mixed model confirmed age, illuminance, and refractive error as significant factors (P < .001). Accounting for the interactions among age, illuminance, and refractive error and establishing their hierarchical dominance can be generalized using the chi-square automated interaction detection method and mixed model. Promoting age-dependent consideration for both illuminance and refractive state is necessary when pupil diameters play significant roles in clinical and manufacturing circumstances.


Asunto(s)
Miopía , Errores de Refracción , Adulto , Factores de Edad , Humanos , Iluminación , Pupila
10.
ACS Appl Polym Mater ; 4(5): 3294-3303, 2022 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-35601463

RESUMEN

Ineffective sorting of post-consumer plastics remains one of the major obstacles in the recycling of plastics. Consequently, these highly heterogeneous, mixed post-consumer plastics will end up in landfill or have to be incinerated as repurposing them directly would lead to a polymer blend with inferior quality for many end-uses. In this work, we demonstrate the use of carbon fibers (CFs) to practically upgrade the mechanical properties of mixed plastics, adding value to them. This will create a stronger demand for mixed plastics to be used in various engineering applications. Using polyethylene terephthalate (PET) and polypropylene (PP) as the model immiscible polymer blend, we showed that the incorporation of CFs increased the tensile, flexural, and single-edge notched fracture toughness of the resulting CF-reinforced PET/PP composite blends. Despite the high environmental burden associated with the production of CFs, cradle-to-grave life-cycle analysis showed that CF-reinforced PET/PP composites have a lower environmental impact than the life-cycle scenarios of "doing nothing" and repurposing immiscible PET/PP blends as it is without CF reinforcement. This can be attributed to the weight saving achieved, a direct result of their higher mechanical performance. Our work opens up opportunities for the use of mixed plastics in various higher value applications such that they can be diverted away from landfill or incineration, in line with the concept of circular economy.

12.
Cell Death Dis ; 12(11): 1054, 2021 11 06.
Artículo en Inglés | MEDLINE | ID: mdl-34743196

RESUMEN

How pathogenesis of inflammatory bowel disease (IBD) depends on the complex interplay of host genetics, microbiome and the immune system is not fully understood. Here, we showed that Downstream of Kinase 3 (DOK3), an adapter protein involved in immune signaling, confers protection of mice from dextran sodium sulfate (DSS)-induced colitis. DOK3-deficiency promotes gut microbial dysbiosis and enhanced colitis susceptibility, which can be reversed by the transfer of normal microbiota from wild-type mice. Mechanistically, DOK3 exerts its protective effect by suppressing JAK2/STAT3 signaling in colonic neutrophils to limit their S100a8/9 production, thereby maintaining gut microbial ecology and colon homeostasis. Hence, our findings reveal that the immune system and microbiome function in a feed-forward manner, whereby DOK3 maintains colonic neutrophils in a quiescent state to establish a gut microbiome essential for intestinal homeostasis and protection from IBD.


Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Calgranulina A/metabolismo , Calgranulina B/metabolismo , Homeostasis , Intestinos/metabolismo , Janus Quinasa 2/metabolismo , Neutrófilos/metabolismo , Factor de Transcripción STAT3/metabolismo , Proteínas Adaptadoras Transductoras de Señales/deficiencia , Animales , Colitis/genética , Colitis/patología , Modelos Animales de Enfermedad , Susceptibilidad a Enfermedades , Disbiosis/complicaciones , Disbiosis/microbiología , Regulación de la Expresión Génica , Mucosa Intestinal/patología , Intestinos/microbiología , Intestinos/patología , Ratones , Microbiota , Transducción de Señal
13.
ACS Synth Biol ; 10(12): 3422-3434, 2021 12 17.
Artículo en Inglés | MEDLINE | ID: mdl-34767345

RESUMEN

Bacteria proficient at producing cellulose are an attractive synthetic biology host for the emerging field of Engineered Living Materials (ELMs). Species from the Komagataeibacter genus produce high yields of pure cellulose materials in a short time with minimal resources, and pioneering work has shown that genetic engineering in these strains is possible and can be used to modify the material and its production. To accelerate synthetic biology progress in these bacteria, we introduce here the Komagataeibacter tool kit (KTK), a standardized modular cloning system based on Golden Gate DNA assembly that allows DNA parts to be combined to build complex multigene constructs expressed in bacteria from plasmids. Working in Komagataeibacter rhaeticus, we describe basic parts for this system, including promoters, fusion tags, and reporter proteins, before showcasing how the assembly system enables more complex designs. Specifically, we use KTK cloning to reformat the Escherichia coli curli amyloid fiber system for functional expression in K. rhaeticus, and go on to modify it as a system for programming protein secretion from the cellulose producing bacteria. With this toolkit, we aim to accelerate modular synthetic biology in these bacteria, and enable more rapid progress in the emerging ELMs community.


Asunto(s)
Celulosa , Ingeniería Genética , Celulosa/genética , Clonación Molecular , Plásmidos/genética , Biología Sintética
14.
Medicine (Baltimore) ; 100(32): e26938, 2021 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-34397944

RESUMEN

BACKGROUND: Glaucoma, is the most common cause of irreversible visual deficits, presents as an injury to the optic nerve and it is mainly associated with elevated intraocular pressure. The main symptom of glaucoma is a reduction of the visual field, which is usually a source of complaint at the advanced stage of disease. Because of visual deficit, gait dysfunctions, including low gait speed and increased bumping into objects, postural sway, and falling are occurred. Many studies have used stopwatch or motion-sensing devices to report on gait function following glaucoma. However, there are few reports on gait dysfunction assessed by examining foot pressure. This study investigated gait ability following glaucoma according to different gait conditions by assessing foot pressure. METHODS: Thirty older adults (15 in the sex- and age-matched normal group and 15 in the glaucoma group) were recruited for this study. All participants were walked under 2 different gait conditions in an F-scan system and the subject' assessments were randomly assigned to rule out the order effect. Conditions included: gait over an obstacle in a straight 6 m path, gait in a straight path without an obstacle in the 6 m path. Gait variables included cadence, gait cycle, stance time, center of force (COF) deviation, and COF excursion. About 10 minutes were taken for gait evaluation. RESULTS: When walking without an obstacle on a 6 m path, there were significant differences between the 2 groups in gait speed, cadence, gait cycle, and stance time (P < .05). There were significant differences when walking with an obstacle on a 6 m path (P < .05). Two-way analysis of variance showed significant effects associated with "glaucoma" not gait condition on all outcomes except for COF deviation and excursion. Also, there was no the interaction effect between "glaucoma" and "gait condition." CONCLUSION: We demonstrated that glaucoma patients selected the gait strategy such as lower gait function in both gait conditions particularly, slower gait speed and cadence and longer gait cycle and stance time, as determined by examining foot pressure. We believe that our results could help to improve the quality of life of patients with glaucoma.


Asunto(s)
Pie/fisiopatología , Marcha/fisiología , Glaucoma/fisiopatología , Calidad de Vida , Zapatos , Caminata/fisiología , Anciano , Fenómenos Biomecánicos , Estudios Transversales , Femenino , Humanos , Masculino , Equilibrio Postural/fisiología , Presión , Velocidad al Caminar/fisiología
15.
Microbiol Spectr ; 9(1): e0034221, 2021 09 03.
Artículo en Inglés | MEDLINE | ID: mdl-34346748

RESUMEN

As the COVID-19 pandemic progresses, there is an increasing need for rapid, accessible assays for SARS-CoV-2 detection. We present a clinical evaluation and real-world implementation of the INDICAID COVID-19 rapid antigen test (INDICAID rapid test). A multisite clinical evaluation of the INDICAID rapid test using prospectively collected nasal (bilateral anterior) swab samples from symptomatic subjects was performed. The INDICAID rapid test demonstrated a positive percent agreement (PPA) and negative percent agreement (NPA) of 85.3% (95% confidence interval [95% CI], 75.6% to 91.6%) and 94.9% (95% CI, 91.6% to 96.9%), respectively, compared to laboratory-based reverse transcriptase PCR (RT-PCR) using nasal specimens. The INDICAID rapid test was then implemented at COVID-19 outbreak screening centers in Hong Kong as part of a testing algorithm (termed "dual-track") to screen asymptomatic individuals for prioritization for confirmatory RT-PCR testing. In one approach, preliminary positive INDICAID rapid test results triggered expedited processing for laboratory-based RT-PCR, reducing the average time to confirmatory result from 10.85 h to 7.0 h. In a second approach, preliminary positive results triggered subsequent testing with an onsite rapid RT-PCR, reducing the average time to confirmatory result to 0.84 h. In 22,994 asymptomatic patients, the INDICAID rapid test demonstrated a PPA of 84.2% (95% CI, 69.6% to 92.6%) and an NPA of 99.9% (95% CI, 99.9% to 100%) compared to laboratory-based RT-PCR using combined nasal/oropharyngeal specimens. The INDICAID rapid test has excellent performance compared to laboratory-based RT-PCR testing and, when used in tandem with RT-PCR, reduces the time to confirmatory positive result. IMPORTANCE Laboratory-based RT-PCR, the current gold standard for COVID-19 testing, can require a turnaround time of 24 to 48 h from sample collection to result. The delayed time to result limits the effectiveness of centralized RT-PCR testing to reduce transmission and stem potential outbreaks. To address this, we conducted a thorough evaluation of the INDICAID COVID-19 rapid antigen test, a 20-minute rapid antigen test, in both symptomatic and asymptomatic populations. The INDICAID rapid test demonstrated high sensitivity and specificity with RT-PCR as the comparator method. A dual-track testing algorithm was also evaluated utilizing the INDICAID rapid test to screen for preliminary positive patients, whose samples were then prioritized for RT-PCR testing. The dual-track method demonstrated significant improvements in expediting the reporting of positive RT-PCR test results compared to standard RT-PCR testing without prioritization, offering an improved strategy for community testing and controlling SARS-CoV-2 outbreaks.


Asunto(s)
Antígenos Virales/análisis , Enfermedades Asintomáticas , Prueba de COVID-19/métodos , COVID-19/diagnóstico , COVID-19/inmunología , SARS-CoV-2/aislamiento & purificación , Adulto , Técnicas de Laboratorio Clínico/métodos , Reacciones Falso Negativas , Reacciones Falso Positivas , Femenino , Hong Kong , Humanos , Masculino , Tamizaje Masivo/métodos , Persona de Mediana Edad , Pandemias , Reacción en Cadena de la Polimerasa , SARS-CoV-2/genética , Sensibilidad y Especificidad , Manejo de Especímenes , Factores de Tiempo , Adulto Joven
16.
Nat Commun ; 12(1): 5027, 2021 08 19.
Artículo en Inglés | MEDLINE | ID: mdl-34413311

RESUMEN

Engineered living materials (ELMs) based on bacterial cellulose (BC) offer a promising avenue for cheap-to-produce materials that can be programmed with genetically encoded functionalities. Here we explore how ELMs can be fabricated in a modular fashion from millimetre-scale biofilm spheroids grown from shaking cultures of Komagataeibacter rhaeticus. Here we define a reproducible protocol to produce BC spheroids with the high yield bacterial cellulose producer K. rhaeticus and demonstrate for the first time their potential for their use as building blocks to grow ELMs in 3D shapes. Using genetically engineered K. rhaeticus, we produce functionalized BC spheroids and use these to make and grow patterned BC-based ELMs that signal within a material and can sense and report on chemical inputs. We also investigate the use of BC spheroids as a method to regenerate damaged BC materials and as a way to fuse together smaller material sections of cellulose and synthetic materials into a larger piece. This work improves our understanding of BC spheroid formation and showcases their great potential for fabricating, patterning and repairing ELMs based on the promising biomaterial of bacterial cellulose.


Asunto(s)
Acetobacteraceae/crecimiento & desarrollo , Bioingeniería/métodos , Biopelículas , Celulosa/química , Ingeniería Genética/métodos , Medicina Regenerativa/métodos , Acetobacteraceae/química , Acetobacteraceae/aislamiento & purificación , Celulosa/aislamiento & purificación
17.
Preprint en Inglés | medRxiv | ID: ppmedrxiv-21259741

RESUMEN

IntroductionVaccination is critical in controlling the coronavirus disease 19 (COVID-19) pandemic. However, vaccine perception and acceptance among pregnant and lactating women is unknown in Singapore. We aimed to determine the acceptance of COVID-19 vaccination among these two groups of women in Singapore, and factors associated with vaccine acceptance. MethodsWe conducted an anonymous, online survey on the perception and acceptance of the COVID-19 vaccine in pregnant and lactating women at a tertiary hospital in Singapore from 1st March to 31st May 2021. Information on demographics and knowledge were collected, and these factors were assessed for their relationship with vaccine acceptance. ResultsA total of 201 pregnant and 207 lactating women participated. Vaccine acceptance rates in pregnant and lactating women were 30.3% and 16.9% respectively. Pregnant women who were unsure or unwilling to take the vaccine cited concerns about safety of the vaccine during pregnancy (92.9%), while lactating women were concerned about potential long-term negative effects on the breastfeeding child (75.6%). Other factors significantly associated with vaccine acceptance included a lower monthly household income or education level, appropriate knowledge regarding vaccine mechanism and higher perceived maternal risk of COVID-19. Most pregnant (70.0%) and lactating women (83.7%) were willing to take the vaccine only when more safety data during pregnancy and breastfeeding were available. ConclusionsCOVID-19 vaccine acceptance was low among pregnant and lactating women in Singapore. Addressing safety concerns when more data is available and education on mechanism of vaccine action will likely improve acceptance among these women.

19.
RSC Adv ; 11(45): 28352-28360, 2021 Aug 16.
Artículo en Inglés | MEDLINE | ID: mdl-35480772

RESUMEN

Hydrogels derived from TEMPO-oxidised cellulose nanofibrils (TOCNs) are not robust and inherently water unstable if the TOCNs are not crosslinked or coated with a water-swellable polymer. Furthermore, the manufacturing of self-standing TOCN films is still a challenge due to the small TOCN diameter and the viscosifying effect of TOCNs. Here, we report the TEMPO-mediated oxidation of bacterial cellulose (BC) nanopaper as a route to produce robust and water stable TOCN hydrogels without the need of additional additives or crosslinking steps. Pristine BC pellicle was first press-dried into a dried and well-consolidated BC nanopaper, followed by TEMPO-oxidation at various NaClO concentrations. The oxidation reaction introduced carboxylate moieties onto the exposed BC nanofibrils within the nanopaper network structure. This then led to the expansion and swelling of the nanopaper into a hydrogel. A swelling ratio of up to 100 times the original thickness of the BC nanopaper was observed upon TEMPO-oxidation. The water retention value of the TEMPO-oxidised BC hydrogels was also found to increase with increasing carboxylate content. These TEMPO-oxidised BC hydrogels were found to be robust and water-stable, even under prolonged (>1 month) magnetic stirring in water. We further showed that high grammage self-standing TOCN films (100 g m-2) can be fabricated as simple as press-drying these water stable TEMPO-oxidised BC hydrogels without the need of vacuum-assisted filtration or slow-drying, which is typically the rate-limiting step in the manufacturing of TOCN films.

20.
Clin Transl Immunology ; 9(10): e1200, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33101678

RESUMEN

OBJECTIVE: Adoptive immunotherapy with ex vivo expanded tumor-specific T cells has potential as anticancer therapy. Preferentially expressed antigen in melanoma (PRAME) is an attractive target overexpressed in several cancers including melanoma and acute myeloid leukaemia (AML), with low expression in normal tissue outside the gonads. We developed a GMP-compliant manufacturing method for PRAME-specific T cells from healthy donors for adoptive immunotherapy. METHODS: Mononuclear cells were pulsed with PRAME 15-mer overlapping peptide mix. After 16 h, activated cells expressing CD137 were isolated with immunomagnetic beads and cocultured with irradiated CD137neg fraction in medium supplemented with interleukin (IL)-2, IL-7 and IL-15. Cultured T cells were restimulated with antigen-pulsed autologous cells after 10 days. Cellular phenotype and cytokine response following antigen re-exposure were assessed with flow cytometry, enzyme-linked immunospot (ELISPOT) and supernatant cytokine detection. Detailed phenotypic and functional analysis with mass cytometry and T-cell receptor (TCR) beta clonality studies were performed on selected cultures. RESULTS: PRAME-stimulated cultures (n = 10) had mean expansion of 2500-fold at day 18. Mean CD3+ percentage was 96% with CD4:CD8 ratio of 4:1. Re-exposure to PRAME peptide mixture showed enrichment of CD4 cells expressing interferon (IFN)-γ (mean: 12.2%) and TNF-α (mean: 19.7%). Central and effector memory cells were 23% and 72%, respectively, with 24% T cells expressing PD1. Mass cytometry showed predominance of Th1 phenotype (CXCR3+/CCR4neg/CCR6neg/Tbet+, mean: 73%) and cytokine production including IL-2, IL-4, IL-8, IL-13 and GM-CSF (2%, 6%, 8%, 4% and 11%, respectively). CONCLUSION: PRAME-specific T cells for adoptive immunotherapy were enriched from healthy donor mononuclear cells. The products were oligoclonal, exhibited Th1 phenotype and produced multiple cytokines.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA