Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 86
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Cell ; 187(10): 2521-2535.e21, 2024 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-38697107

RESUMO

Cancer immunotherapy remains limited by poor antigenicity and a regulatory tumor microenvironment (TME). Here, we create "onion-like" multi-lamellar RNA lipid particle aggregates (LPAs) to substantially enhance the payload packaging and immunogenicity of tumor mRNA antigens. Unlike current mRNA vaccine designs that rely on payload packaging into nanoparticle cores for Toll-like receptor engagement in immune cells, systemically administered RNA-LPAs activate RIG-I in stromal cells, eliciting massive cytokine/chemokine response and dendritic cell/lymphocyte trafficking that provokes cancer immunogenicity and mediates rejection of both early- and late-stage murine tumor models. In client-owned canines with terminal gliomas, RNA-LPAs improved survivorship and reprogrammed the TME, which became "hot" within days of a single infusion. In a first-in-human trial, RNA-LPAs elicited rapid cytokine/chemokine release, immune activation/trafficking, tissue-confirmed pseudoprogression, and glioma-specific immune responses in glioblastoma patients. These data support RNA-LPAs as a new technology that simultaneously reprograms the TME while eliciting rapid and enduring cancer immunotherapy.


Assuntos
Imunoterapia , Lipídeos , RNA , Microambiente Tumoral , Animais , Cães , Feminino , Humanos , Camundongos , Antígenos de Neoplasias/imunologia , Neoplasias Encefálicas/terapia , Neoplasias Encefálicas/imunologia , Vacinas Anticâncer/imunologia , Vacinas Anticâncer/uso terapêutico , Linhagem Celular Tumoral , Citocinas/metabolismo , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Glioblastoma/terapia , Glioblastoma/imunologia , Glioma/terapia , Glioma/imunologia , Imunoterapia/métodos , Camundongos Endogâmicos C57BL , Neoplasias/terapia , Neoplasias/imunologia , RNA/química , RNA/uso terapêutico , RNA Mensageiro/metabolismo , RNA Mensageiro/genética , Lipídeos/química
2.
Cell ; 184(10): 2649-2664.e18, 2021 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-33848463

RESUMO

Receptor tyrosine kinase (RTK)-mediated activation of downstream effector pathways such as the RAS GTPase/MAP kinase (MAPK) signaling cascade is thought to occur exclusively from lipid membrane compartments in mammalian cells. Here, we uncover a membraneless, protein granule-based subcellular structure that can organize RTK/RAS/MAPK signaling in cancer. Chimeric (fusion) oncoproteins involving certain RTKs including ALK and RET undergo de novo higher-order assembly into membraneless cytoplasmic protein granules that actively signal. These pathogenic biomolecular condensates locally concentrate the RAS activating complex GRB2/SOS1 and activate RAS in a lipid membrane-independent manner. RTK protein granule formation is critical for oncogenic RAS/MAPK signaling output in these cells. We identify a set of protein granule components and establish structural rules that define the formation of membraneless protein granules by RTK oncoproteins. Our findings reveal membraneless, higher-order cytoplasmic protein assembly as a distinct subcellular platform for organizing oncogenic RTK and RAS signaling.


Assuntos
Condensados Biomoleculares/metabolismo , Grânulos Citoplasmáticos/metabolismo , Neoplasias/metabolismo , Proteínas de Fusão Oncogênica/metabolismo , Proteínas ras/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Ativação Enzimática , Proteína Adaptadora GRB2/genética , Proteína Adaptadora GRB2/metabolismo , Células HEK293 , Humanos , Proteína SOS1/metabolismo , Transdução de Sinais
3.
Cell ; 174(2): 391-405.e19, 2018 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-29937225

RESUMO

Transposable elements represent nearly half of mammalian genomes and are generally described as parasites, or "junk DNA." The LINE1 retrotransposon is the most abundant class and is thought to be deleterious for cells, yet it is paradoxically highly expressed during early development. Here, we report that LINE1 plays essential roles in mouse embryonic stem cells (ESCs) and pre-implantation embryos. In ESCs, LINE1 acts as a nuclear RNA scaffold that recruits Nucleolin and Kap1/Trim28 to repress Dux, the master activator of a transcriptional program specific to the 2-cell embryo. In parallel, LINE1 RNA mediates binding of Nucleolin and Kap1 to rDNA, promoting rRNA synthesis and ESC self-renewal. In embryos, LINE1 RNA is required for Dux silencing, synthesis of rRNA, and exit from the 2-cell stage. The results reveal an essential partnership between LINE1 RNA, Nucleolin, Kap1, and peri-nucleolar chromatin in the regulation of transcription, developmental potency, and ESC self-renewal.


Assuntos
Fosfoproteínas/metabolismo , Proteínas de Ligação a RNA/metabolismo , Animais , Diferenciação Celular , Linhagem Celular , Autorrenovação Celular , Imunoprecipitação da Cromatina , Retrovirus Endógenos/genética , Feminino , Proteínas de Homeodomínio/antagonistas & inibidores , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Hibridização in Situ Fluorescente , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Células-Tronco Embrionárias Murinas/citologia , Células-Tronco Embrionárias Murinas/metabolismo , Oligorribonucleotídeos Antissenso/metabolismo , Fosfoproteínas/antagonistas & inibidores , Fosfoproteínas/genética , Interferência de RNA , RNA Ribossômico/metabolismo , Proteínas de Ligação a RNA/antagonistas & inibidores , Proteínas de Ligação a RNA/genética , Proteína 28 com Motivo Tripartido/antagonistas & inibidores , Proteína 28 com Motivo Tripartido/genética , Proteína 28 com Motivo Tripartido/metabolismo , Regulação para Cima , Nucleolina
4.
Proc Natl Acad Sci U S A ; 120(37): e2305380120, 2023 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-37669372

RESUMO

Proactively programming materials toward target nonlinear mechanical behaviors is crucial to realize customizable functions for advanced devices and systems, which arouses persistent explorations for rapid and efficient inverse design strategies. Herein, we propose a "mechanical Fourier transform" strategy to program mechanical behaviors of materials by mimicking the concept of Fourier transform. In this strategy, an arbitrary target force-displacement curve is decomposed into multiple cosine curves and a constant curve, each of which is realized by a rationally designed multistable module in an array-structured metamaterial. Various target curves with distinct shapes can be rapidly programmed and reprogrammed through only amplitude modulation on the modules. Two exemplary metamaterials are demonstrated to validate the strategy with a macroscale prototype based on magnet lattice and a microscale prototype based on an etched silicon wafer. This strategy applies to a variety of scales, constituents, and structures, and paves a way for the property programming of materials.

5.
Actas Esp Psiquiatr ; 52(1): 28-36, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38454900

RESUMO

BACKGROUND: Depressive disorder is a chronic mental illness characterized by persistent low mood as its primary clinical symptom. Currently, psychotherapy and drug therapy stand as the primary treatment modalities in clinical practice, offering a certain degree of relief from negative emotions for patients. Nevertheless, sole reliance on drug therapy exhibits a delayed impact on neurotransmitters, and long-term usage often results in adverse side effects such as nausea, drowsiness, and constipation, significantly impeding medication adherence. This study aims to investigate the impact of combining transcranial magnetic stimulation with sertraline on the cognitive level, inflammatory response, and neurological function in patients with depressive disorder who engage in non-suicidal self-injury (NSSI) behavior. METHODS: A total of 130 depressive patients NSSI behavior, who were admitted to our hospital from December 2020 to February 2023, were selected as the subjects for this research. The single-group (65 cases) received treatment with oral sertraline hydrochloride tablets, while the combination group (65 cases) underwent repetitive transcranial magnetic stimulation (rTMS) in conjunction with sertraline. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was utilized to assess the depression status and cognitive function levels of both groups. Additionally, the enzyme-linked immunosorbent assay (ELISA) was employed to measure serum levels of inflammatory factors, including tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6). Furthermore, serum levels of neurotransmitters (norepinephrine (NE), dopamine (DA), 5-hydroxytryptamine (5-HT)) and neuro-cytokines (brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), glial fibrillary acidic protein (GFAP)) were assessed. The clinical effects of the interventions on both groups were then evaluated. RESULTS: Following the treatment, the combination group exhibited significantly higher levels of immediate memory, delayed memory, attention, visual function, and language function compared to the single group, with statistically significant differences (p < 0.05). Additionally, the serum levels of TNF-α, IL-1ß, IL-6, and GFAP in the combination group were lower than those in the single group, while the levels of BDNF and NGF were higher in the combination group compared to the single group. These differences were also statistically significant (p < 0.05). Simultaneously, the total clinical effective rate in the combination group reached 95.38%, surpassing the 84.61% observed in the single group, and the disparity between the two groups was statistically significant (p < 0.05). CONCLUSIONS: The combined use of rTMS and sertraline in treating patients with depressive disorder exhibiting NSSI behavior has proven to be effective in enhancing cognitive function, mitigating inflammatory responses, and elevating levels of neurotransmitters and nerve cytokines in the patients.


Assuntos
Transtorno Depressivo , Comportamento Autodestrutivo , Humanos , Sertralina/uso terapêutico , Estimulação Magnética Transcraniana/métodos , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Fator de Necrose Tumoral alfa , Interleucina-6 , Fator de Crescimento Neural , Citocinas/metabolismo , Cognição , Neurotransmissores
6.
Biomacromolecules ; 24(1): 332-343, 2023 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-36562543

RESUMO

Natural fiber-reinforced biocomposites with excellent mechanical and biological properties have attractive prospects for internal medical devices. However, poor interfacial adhesion between natural silk fiber and the polymer matrix has been a disturbing issue for such applications. Herein, rigid-flexible agents, such as polydopamine (PDA) and epoxy soybean oil (ESO), were introduced to enhance the interfacial adhesion between Antheraea pernyi (Ap) silk and a common medical polymer, polycaprolactone (PCL). We compared two strategies of depositing PDA first (Ap-PDA-ESO) and grafting ESO first (Ap-ESO-PDA). The rigid-flexible interfacial agents introduced multiple molecular interactions at the silk-PCL interface. The "Ap-PDA-ESO" strategy exhibited a greater enhancement in interfacial adhesion, and interfacial toughening mechanisms were proposed. This work sheds light on engineering strong and tough silk fiber-based biocomposites for biomedical applications.


Assuntos
Polímeros , Seda , Poliésteres
7.
Int J Mol Sci ; 24(15)2023 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-37569866

RESUMO

Biomechanical forces are of fundamental importance in biology, diseases, and medicine. Mechanobiology is an emerging interdisciplinary field that studies how biological mechanisms are regulated by biomechanical forces and how physical principles can be leveraged to innovate new therapeutic strategies. This article reviews state-of-the-art mechanobiology knowledge about the yes-associated protein (YAP), a key mechanosensitive protein, and its roles in the development of drug resistance in human cancer. Specifically, the article discusses three topics: how YAP is mechanically regulated in living cells; the molecular mechanobiology mechanisms by which YAP, along with other functional pathways, influences drug resistance of cancer cells (particularly lung cancer cells); and finally, how the mechanical regulation of YAP can influence drug resistance and vice versa. By integrating these topics, we present a unified framework that has the potential to bring theoretical insights into the design of novel mechanomedicines and advance next-generation cancer therapies to suppress tumor progression and metastasis.


Assuntos
Neoplasias Pulmonares , Fatores de Transcrição , Humanos , Fenômenos Biomecânicos , Fatores de Transcrição/metabolismo , Neoplasias Pulmonares/tratamento farmacológico , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Resistencia a Medicamentos Antineoplásicos
8.
Nano Lett ; 21(12): 5158-5166, 2021 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-34097422

RESUMO

Cancer patients suffer from the toxicity of chemotherapy. Antidote, given as a remedy limiting poison, is an effective way to counteract toxicity. However, few antidotes abrogate chemotoxicity without compromising the therapeutic efficacy. Herein, a rationally designed nanoantidote can neutralize chemo-agents in normal cells but not enter tumors and thus would not interfere with the efficacy of tumor treatment. The nanoantidote, consisting of a dendrimer core wrapped by reductive cysteine, captures Temozolomide (TMZ, the glioblastoma standard chemotherapy). Meanwhile, thanks to the blood-brain barrier (BBB) and the size of the nanoantidote, the nanoantidote cannot enter glioblastoma. In murine models, the nanoantidote distributes in normal tissues without crossing the BBB, so it markedly reduces the chemotoxicity of TMZ and retains the original TMZ therapeutic efficacy. With most nanotechnologies focusing on antitumor treatment, this detoxicating strategy demonstrates a nanoplatform to reduce chemotoxicity using physiology barriers and introduces a new approach to nanomedicine for cancer chemotherapy.


Assuntos
Neoplasias Encefálicas , Glioblastoma , Animais , Antineoplásicos Alquilantes/farmacologia , Antineoplásicos Alquilantes/uso terapêutico , Barreira Hematoencefálica , Neoplasias Encefálicas/tratamento farmacológico , Linhagem Celular Tumoral , Glioblastoma/tratamento farmacológico , Humanos , Camundongos , Temozolomida/farmacologia , Temozolomida/uso terapêutico , Ensaios Antitumorais Modelo de Xenoenxerto
9.
Nano Lett ; 21(11): 4744-4752, 2021 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-34010008

RESUMO

Nanovaccines are of increasing scrutiny due to their plasticity in size, composition, and surface properties to enhance antigenicity. However, inevitable absorption of plasma proteins affects the in vivo fate of nanovaccines by reshaping biological identity. Herein IgM was validated as a self-adjuvant by regulating antigen-presenting cells recognition of liposome-based nanovaccines. DCDX-modified liposomes with loading of ovalbumin (DCDX-sLip/OVA) heavily absorbed IgM via electrostatic interaction, demonstrating significant splenic B cells targeting. IgM absorbed on DCDX-sLip/OVA enhanced antigen uptake and presentation by both IgM-complement and IgM-FcµR pathways. DCDX-sLip/OVA induced a stronger IgG1 titer than ovalbumin-loaded plain liposomes (sLip/OVA) while maintaining a comparably high level of IgG2a titer with high biosafety, indicating that IgM absorption after DCDX modification could improve the antigenicity by enhancing the Th2-polarized immune response. The present work suggested manipulation of IgM absorption may provide a new impetus to improve in vivo performance of nanovaccines.


Assuntos
Adjuvantes Imunológicos , Lipossomos , Antígenos , Imunoglobulina G , Ovalbumina
10.
Phytother Res ; 34(1): 104-117, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31515889

RESUMO

The side effects of docetaxel have limited its antitumor performances in the treatment of nonsmall cell lung cancer (NSCLC). To address the problem, baicalein, a bioactive flavone that exhibits antitumor activity, was combined with docetaxel so as to achieve better efficacy and lower toxicity. The combination treatment enhanced the stabilization of microtubules and halted the cell-cycle progression, thus synergistically inhibiting the proliferation and inducing the apoptosis of A549 cells and Lewis lung carcinoma cells. The decreased expression of Cyclin-dependent kinase 6 and Cyclin B1 confirmed its regulation in cell cycle, with ß-catenin being an important upstream effector, as evidenced by the decreased expression in the cytoplasm and nucleus as well as the attenuated aggregation in the nucleus. Furthermore, baicalein plus docetaxel evinced better antitumor efficacy by the suppressed tumor growth, increased apoptosis, and decreased tumor angiogenesis in vivo, with no increased toxicity discovered in both tumor-bearing and non-tumor-bearing mice, and an improvement in therapeutic index. This study has demonstrated that baicalein plus docetaxel is an appropriate combination simultaneously with augmented antitumor efficacy and acceptable safety, which might be a promising strategy for patients with advanced NSCLC.


Assuntos
Antioxidantes/uso terapêutico , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Quimioterapia Combinada/métodos , Flavanonas/uso terapêutico , Neoplasias Pulmonares/tratamento farmacológico , beta Catenina/metabolismo , Animais , Antioxidantes/farmacologia , Carcinoma Pulmonar de Células não Pequenas/patologia , Docetaxel/farmacologia , Docetaxel/uso terapêutico , Flavanonas/farmacologia , Humanos , Neoplasias Pulmonares/patologia , Masculino , Camundongos
11.
Clin Sci (Lond) ; 133(11): 1215-1228, 2019 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-31101724

RESUMO

Background: Although junctional adhesion molecule-like protein (JAML) has recently been implicated in leukocyte recruitment during inflammation and wound repair, its role in atherosclerosis remains to be elucidated. Methods and results: First, we showed that JAML was strongly expressed in atherosclerotic plaques of cardiovascular patients. Similar results were obtained with atherosclerotic plaques of ApoE-/- mice. Co-immunofluorescence staining showed that JAML was mainly expressed in macrophages. Enhanced expression of JAML in cultured macrophages was observed following exposure of the cells to oxLDL. The functional role of JAML in atherosclerosis and macrophages function was assessed by interference of JAML with shRNA in vivo and siRNA in vitro Silencing of JAML in mice significantly attenuated atherosclerotic lesion formation, reduced necrotic core area, increased plaque fibrous cap thickness, decreased macrophages content and inflammation. In addition, histological staining showed that JAML deficiency promoted plaques to stable phenotype. In vitro, JAML siRNA treatment lowered the expression of inflammatory cytokines in macrophages treated with oxLDL. The mechanism by which JAML mediated the inflammatory responses may be related to the ERK/NF-κB activation. Conclusions: Our results demonstrated that therapeutic drugs which antagonize the function of JAML may be a potentially effective approach to attenuate atherogenesis and enhance plaque stability.


Assuntos
Aterosclerose/metabolismo , Moléculas de Adesão Celular/metabolismo , Camundongos Knockout para ApoE/metabolismo , Placa Aterosclerótica/metabolismo , Animais , Apolipoproteínas E/metabolismo , Apolipoproteínas E/fisiologia , Aterosclerose/etiologia , Western Blotting , Moléculas de Adesão Celular/fisiologia , Imunofluorescência , Inativação Gênica , Humanos , Moléculas de Adesão Juncional , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Células RAW 264.7 , RNA Interferente Pequeno/metabolismo , Reação em Cadeia da Polimerase em Tempo Real
12.
Mol Pharm ; 16(2): 737-743, 2019 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-30652875

RESUMO

Honokiol (HNK) is a small-molecule lignin extracted from Magnolia Officinalis, demonstrating high potency in promoting nonrapid eye movement (NREM) sleep by modulating the benzodiazepine site of the GABAA receptor. However, the clinical use of HNK in the treatment of insomnia is restricted by its extremely low oral bioavailability. In the present work, enhanced oral bioavailability of HNK was achieved by loading it into poly lactide-glycolide acid microparticles (HNK-MP). After oral administration, HNK-MP demonstrated 15-fold increase of AUC0-12 h in comparison to free HNK. The maximum blood concentration ( Cmax) of HNK in HNK-MP-treated rats was 3.6 µg/mL at 2 h after oral administration, which was 6.5-fold of that in free HNK-treated rats. Oral administration of HNK-MP (20 mg/kg) efficiently increased NREM sleep by 60% by enhancing the transition from wakefulness to NREM sleep in rats. The biosafety of HNK-MP was assessed in vivo, and no damage occurred in the gastrointestinal tract. The present study provides a promising oral HNK formulation for the treatment of insomnia.


Assuntos
Compostos de Bifenilo/farmacologia , Movimentos Oculares/efeitos dos fármacos , Lignanas/farmacologia , Administração Oral , Animais , Benzodiazepinas/farmacologia , Compostos de Bifenilo/administração & dosagem , Portadores de Fármacos/química , Eletroencefalografia , Feminino , Lignanas/administração & dosagem , Ratos , Ratos Sprague-Dawley , Receptores de GABA-A/metabolismo , Sono de Ondas Lentas/efeitos dos fármacos
13.
Mol Pharm ; 16(2): 907-913, 2019 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-30666875

RESUMO

Peptide ligands have been exploited as versatile tools to facilitate targeted delivery of nanocarriers. However, the effects of peptide ligands on immunocompatibility and therapeutic efficacy of liposomes remain intricate. Here, a short and stable brain targeted peptide ligand D8 was modified on the surface of doxorubicin-loaded liposomes (D8-sLip/DOX), demonstrating prolonged blood circulation and lower liver distribution in comparison to the long and stable D-peptide ligand DCDX-modified doxorubicin-loaded liposomes (DCDX-sLip/DOX) by mitigating natural IgM absorption. Despite the improved pharmacokinetic profiles, D8-sLip/DOX exhibited comparable brain targeting capacity in ICR mice and antiglioblastoma efficacy to DCDX-sLip/DOX in nude mice bearing intracranial glioblastoma. However, dramatic accumulation of DCDX-sLip/DOX in liver (especially during the first 8 h after intravenous injection) resulted in pathological symptoms, including nuclei swelling, necrosis of liver cells, and inflammation. These results suggest that short peptide ligand-mediated brain-targeted drug delivery systems possessing enhanced immunocompatibility are promising to facilitate efficient brain transport with improved biosafety.


Assuntos
Encéfalo/metabolismo , Peptídeos/metabolismo , Animais , Barreira Hematorretiniana , Doxorrubicina/química , Doxorrubicina/metabolismo , Sistemas de Liberação de Medicamentos , Lipossomos/química , Lipossomos/metabolismo , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Ratos , Ratos Sprague-Dawley
14.
Biomacromolecules ; 20(6): 2295-2304, 2019 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-31070895

RESUMO

Natural silkworm silks have been applied to reinforce epoxy resin to achieve sub-ambient and impact toughness in the composite. However, the molecular interactions at the silk fiber-matrix interface of the composite are poorly understood. In this work, silk fibroin extracted from Bombyx mori silk is blended with an epoxy resin polymer system to study the molecular interactions between silk fibroin, epoxy compounds, and hardeners. The effects of chemical crosslinks between epoxy groups and hardeners or silk fibroin, as well as physical crosslinks in the ß-sheet structure of silk fibroin, were discussed on the thermal stability, glass transition behavior, and mechanical properties of the blend films. A relationship between the crosslinking structure and mechanical properties for the films is proposed to enlighten on the toughening mechanisms. The findings would provide insights into forming strong and tough silk fibroin material as well as understanding the interface interactions of silk-epoxy composites.


Assuntos
Resinas Epóxi/química , Fibroínas/química , Membranas Artificiais , Animais , Bombyx
15.
Macromol Rapid Commun ; 40(23): e1900389, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31692142

RESUMO

Regenerated silk fibroin (RSF) is a promising biomedical material, but the poor mechanical properties of RSF hydrogels may hinder the use as structural components. Herein, an equilibrium RSF hydrogel is prepared and optimized based on the double network (DN) concept. After sufficient soaking in water and removal of small molecules, the equilibrium RSF DN hydrogels prove stable in water, strong, highly extensible, and tough with 0.26-0.44 MPa tensile strength, 500-900% elongation, and 2 MJ m-3 work of extension. The combination of high strength and extensibility is attributed to the homogeneous morphology and the hydrophobic interactions and hydrogen bonding between the two networks. The strategy in this work overcomes the previous issue of swelling and eventual fracture of as-prepared RSF/SDS DN hydrogels in water. In addition, such mechanically superior RSF DN hydrogels also display low cytotoxicity. It concludes that the elastic and tough RSF DN hydrogels could be engineered by introducing widely used polymer networks, and the hydrogels from inexpensive, environmentally friendly, and biocompatible silk fibroin may hold great potential in biomedical applications.


Assuntos
Fibroínas/química , Hidrogéis/química , Resistência à Tração , Animais , Materiais Biocompatíveis/química , Linhagem Celular , Teste de Materiais , Camundongos , Tamanho da Partícula , Polímeros/química , Propriedades de Superfície
16.
J Chem Phys ; 149(16): 163331, 2018 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-30384691

RESUMO

Dynamic fluorescence-based single-molecule imaging of λ-DNA molecules driven through agarose hydrogels by DC electric fields reveals that passage through the hydrogel (98.5% water content) induces mobility orthogonal to the external field. Tortuous paths followed by the DNA molecules, which are heavily entangled in the hydrogel mesh as their contour length is nearly 100 times the hydrogel mesh size of 200 nm, cause them to appear to diffuse orthogonal to the driving force. The higher the driving field, from 2 to 16 V/cm, the higher the off-axis dispersion is, over the same time interval. We measure the off-axis displacement distribution over 3 orders of magnitude of probability density and find a master curve after normalizing for time (t) elapsed, but the power of time for normalizing increases with the external field, from t0.25 to t0.6 with increasing field. Comparing trajectories over the same distance traveled in the electric field direction, we observe whereas for the highest field strengths DNA molecules come closest to taking the shortest trajectory between two points in space, deviations from the shortest trajectory grow larger and larger (up to 40% larger) as one approaches the case of small yet finite external field strength.


Assuntos
DNA/química , Hidrogéis/química , Microscopia de Fluorescência
17.
Biophys J ; 112(6): 1077-1084, 2017 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-28355536

RESUMO

Live imaging of genome has offered important insights into the dynamics of the genome organization and gene expression. The demand to image simultaneously multiple genomic loci has prompted a flurry of exciting advances in multicolor CRISPR imaging, although color-based multiplexing is limited by the need for spectrally distinct fluorophores. Here we introduce an approach to achieve highly multiplexed live recording via correlative CRISPR imaging and sequential DNA fluorescence in situ hybridization (FISH). This approach first performs one-color live imaging of multiple genomic loci and then uses sequential rounds of DNA FISH to determine the loci identity. We have optimized the FISH protocol so that each round is complete in 1 min, demonstrating the identification of seven genomic elements and the capability to sustain reversible staining and washing for up to 20 rounds. We have also developed a correlation-based algorithm to faithfully register live and FISH images. Our approach keeps the rest of the color palette open to image other cellular phenomena of interest, as demonstrated by our simultaneous live imaging of genomic loci together with a cell cycle reporter. Furthermore, the algorithm to register faithfully between live and fixed imaging is directly transferrable to other systems such as multiplex RNA imaging with RNA-FISH and multiplex protein imaging with antibody-staining.


Assuntos
Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , DNA/genética , Genômica , Hibridização in Situ Fluorescente , Imagem Molecular/métodos , Cor , Humanos , Cinética , Coloração e Rotulagem
18.
Soft Matter ; 12(27): 5926-36, 2016 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-27320178

RESUMO

Silks are a family of semi-crystalline structural materials, spun naturally by insects, spiders and even crustaceans. Compared to the characteristic ß-sheet crystalline structure in silks, the non-crystalline structure and its composition deserves more attention as it is equally critical to the filaments' high toughness and strength. Here we further unravel the structure-property relationship in silks using Dynamic Mechanical Thermal Analysis (DMTA). This technique allows us to examine the most important structural relaxation event of the disordered structure the disordered structure, the glass transition (GT), in native silk fibres of the lepidopteran Bombyx mori and Antheraea pernyi and the spider Nephila edulis. The measured glass transition temperature Tg, loss tangent tan δ and dynamic storage modulus are quantitatively modelled based on Group Interaction Modelling (GIM). The "variability" issue in native silks can be conveniently explained by the different degrees of structural disorder as revealed by DMTA. The new insights will facilitate a more comprehensive understanding of the structure-property relations for a wide range of biopolymers.

19.
Pacing Clin Electrophysiol ; 38(10): 1181-91, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26172918

RESUMO

BACKGROUND: Long-term effects of ganglionated plexi (GP) ablation on sinoatrial node (SAN) and atrioventricular node (AVN) remain unclear. This study is to investigate the long-term effects of ablation of cardiac anterior right GP (ARGP) and inferior right GP (IRGP) on function and structure of SAN and AVN in canine. METHODS: Thirty-two dogs were randomly divided into an operated group (n = 24) and sham-operated group (n = 8). ARGP and IRGP were ablated in operated group which was randomly divided into three subgroups according to the period of evaluation after operation (1 month, 6 months, 12 months). The functional and histological characteristics of SAN and AVN, as well as the expression of connexin (Cx) 43 and Cx 45 in SAN and AVN, were evaluated before and after ablation. RESULTS: Resting heart rate was increased and AVN effective refractory period was prolonged and sinus node recovery time (SNRT) and corrected SNRT were shortened immediately after ablation. These changes were reverted to preablation level after 1 month. At 1 month, ventricular rate during atrial fibrillation was slowed, atria-His intervals were prolonged, and Cx43 and Cx45 expression in SAN and AVN were downregulated. At 6 months, all changes were reverted to preablation level. The histological characteristics of SAN and AVN did not change. CONCLUSION: Ablation of ARGP and IRGP has short-term effects on function and structure of SAN and AVN rather than long-term effects, which suggests that ablation of ARGP and IRGP is safe. Atrioventricular conduction dysfunction after ablation may be related to downregulated Cx43 and Cx45 expression in AVN.


Assuntos
Nó Atrioventricular/fisiopatologia , Sistema Nervoso Autônomo/cirurgia , Ablação por Cateter , Átrios do Coração/cirurgia , Nó Sinoatrial/fisiopatologia , Animais , Nó Atrioventricular/patologia , Nó Atrioventricular/cirurgia , Sistema Nervoso Autônomo/patologia , Sistema Nervoso Autônomo/fisiopatologia , Cães , Átrios do Coração/inervação , Estudos Longitudinais , Nó Sinoatrial/patologia , Nó Sinoatrial/cirurgia , Resultado do Tratamento
20.
Soft Matter ; 10(33): 6321-31, 2014 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-25030083

RESUMO

Variability is a common feature of natural silk fibres, caused by a range of natural processing conditions. Better understanding of variability will not only be favourable for explaining the enviable mechanical properties of animal silks but will provide valuable information for the design of advanced artificial and biomimetic silk-like materials. In this work, we have investigated the origin of variability in forcibly reeled Antheraea pernyi silks from different individuals using dynamic mechanical thermal analysis (DMTA) combined with the effect of polar solvent penetration. Quasi-static tensile curves in different media have been tested to show the considerable variability of tensile properties between samples from different silkworms. The DMTA profiles (as a function of temperature or humidity) through the glass transition region of different silks as well as dynamic mechanical properties after high temperature and water annealing are analysed in detail to identify the origin of silk variability in terms of molecular structures and interactions, which indicate that different hydrogen bonded structures exist in the amorphous regions and they are notably different for silks from different individuals. Solubility parameter effects of solvents are quantitatively correlated with the different glass transitions values. Furthermore, the overall ordered fraction is shown to be a key parameter to quantify the variability in the different silk fibres, which is consistent with DMTA and FTIR observations.


Assuntos
Seda/química , Animais , Simulação por Computador , Umidade , Ligação de Hidrogênio , Teste de Materiais , Fenômenos Mecânicos , Estrutura Molecular , Mariposas , Solubilidade , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier , Estresse Mecânico , Temperatura , Resistência à Tração
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA