Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 9 de 9
Filtrar
1.
Front Psychol ; 13: 837042, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35242088

RESUMO

Since their introduction in the early 2000s, the use of social networking websites has exploded. Many businesses are seeing increased revenue due to their social commerce strategy. Despite the popularity of social commerce websites, some consumers are still hesitate to use them. This study aims to evaluate the factors that influence the adoption of social commerce. A sample of 721 Chinese We Chat users took part in the research. The findings reveal that social capital mediates the positive effect of social commerce adoption and perceived ease of use (PERU) on techno-stress and online impulse purchasing. Likewise, information overloading mediates the positive effect of social commerce adoption and PERU on techno-stress and online impulse purchasing. The findings have implications for both practice and research in understanding social commerce adoption in emerging economies.

2.
Otol Neurotol ; 43(9): e1049-e1055, 2022 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-36006779

RESUMO

BACKGROUND AND OBJECTIVES: Vestibular schwannoma (VS), the most common intercranial schwannoma, originates from the sheath of the vestibular nerve. The growth rate of VS varies greatly, with the tumor enlarging gradually, which can compress the peripheral nerve tissue and reveal corresponding symptoms. This study was aimed to elucidate the growth mechanism of VS by analyzing cellular changes at protein, messenger ribonucleic acid (mRNA), and other molecular levels. METHODS: We determined mRNA and protein levels of ß 2 -microglobulin (ß 2 -M) and nuclear factor κB (NF-κB) in tumors of different sizes using the real-time polymerase chain reaction and Western blotting, respectively. The relationship between these factors was verified in VS primary cells cultured in vitro, and the potential role of ß 2 -M and NF-κB in VS growth was elucidated. RESULTS: In the secretions of freshly isolated tumor tissue cultured for 72 h, the concentration of ß 2 -M was positively correlated with the tumor diameter. Furthermore, tumors with larger diameter showed higher expressions of ß 2 -M and NF-κB at protein and mRNA level. ß 2 -M treatment resulted in elevated protein expression of NF-κB and also its phosphorylated form in vitro. CONCLUSION: ß 2 -M may participate in VS growth by regulating NF-κB and act as a key regulatory molecule in VS tumor growth.


Assuntos
NF-kappa B , Neuroma Acústico , Microglobulina beta-2 , Humanos , NF-kappa B/genética , NF-kappa B/metabolismo , Neuroma Acústico/genética , RNA Mensageiro/metabolismo , Microglobulina beta-2/genética , Microglobulina beta-2/metabolismo
3.
Zhongguo Yi Xue Ke Xue Yuan Xue Bao ; 33(1): 62-5, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21375940

RESUMO

OBJECTIVE: To prepare a rabbit meniscus acellular matrix scaffold and explore the histomorphological and biomechanical properties of the scaffold. METHODS: Rabbit meniscuses were collected and acellularized using a modified eight-step detergent process with hydrogen peroxide, distilled water, Triton X-100, and sodium deoxycholate. Its color and texture were observed. Histomorphological assessment was performed using routine hematoxylin-eosin stain, toluidine blue stain, Saffron stain, Hoechst-33258 stain, and immunohistochemical staining of collagen I. The ultrastructure of the specimens was observed with inverted phase contrast microscopy. Transient recovery rate of deformation, maximal recovery rate of deformation, and maximal compressive strength were tested to determine the biomechanical properties of the scaffold. RESULTS: The processed meniscus was milk-white in color with loose structure. It histologically appeared cell-free, stained positively for collagen I, and had abundant micropores according to phase-contrast microscopy. The transient recovery rate of deformation was (76.65∓4.61)%, the maximal recovery rate of deformation was 100%, and the maximal compressive strength was (4.51∓0.69) N when the specimens were compressed 40%. CONCLUSIONS: The rabbit meniscus acellular matrix scaffold, with numerous micropores, is easy to be recovered from deformation and suitable for the adhesiveness and growth of breeding cells. This scaffold can be used as an ideal implant for future tissue engineering of the meniscus.


Assuntos
Meniscos Tibiais , Engenharia Tecidual , Alicerces Teciduais , Animais , Materiais Biocompatíveis/análise , Fenômenos Biomecânicos , Teste de Materiais , Meniscos Tibiais/química , Meniscos Tibiais/citologia , Meniscos Tibiais/ultraestrutura , Coelhos
4.
Front Cell Dev Biol ; 9: 740303, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34692698

RESUMO

Brain tumors in children and adults are challenging tumors to treat. Malignant primary brain tumors (MPBTs) such as glioblastoma have very poor outcomes, emphasizing the need to better understand their pathogenesis. Developing novel strategies to slow down or even stop the growth of brain tumors remains one of the major clinical challenges. Modern treatment strategies for MPBTs are based on open surgery, chemotherapy, and radiation therapy. However, none of these treatments, alone or in combination, are considered effective in controlling tumor progression. MicroRNAs (miRNAs) are 18-22 nucleotide long endogenous non-coding RNAs that regulate gene expression at the post-transcriptional level by interacting with 3'-untranslated regions (3'-UTR) of mRNA-targets. It has been proven that miRNAs play a significant role in various biological processes, including the cell cycle, apoptosis, proliferation, differentiation, etc. Over the last decade, there has been an emergence of a large number of studies devoted to the role of miRNAs in the oncogenesis of brain tumors and the development of resistance to radio- and chemotherapy. Wherein, among the variety of molecules secreted by tumor cells into the external environment, extracellular vesicles (EVs) (exosomes and microvesicles) play a special role. Various elements were found in the EVs, including miRNAs, which can be transported as part of these EVs both between neighboring cells and between remotely located cells of different tissues using biological fluids. Some of these miRNAs in EVs can contribute to the development of resistance to radio- and chemotherapy in MPBTs, including multidrug resistance (MDR). This comprehensive review examines the role of miRNAs in the resistance of MPBTs (e.g., high-grade meningiomas, medulloblastoma (MB), pituitary adenomas (PAs) with aggressive behavior, and glioblastoma) to chemoradiotherapy and pharmacological treatment. It is believed that miRNAs are future therapeutic targets in MPBTs and such the role of miRNAs needs to be critically evaluated to focus on solving the problems of resistance to therapy this kind of human tumors.

5.
Chem Sci ; 12(11): 4057-4062, 2021 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-34163676

RESUMO

Vasopressin (VP) and oxytocin (OT) are cyclic neuropeptides that regulate fundamental physiological functions via four G protein-coupled receptors, V1aR, V1bR, V2R, and OTR. Ligand development remains challenging for these receptors due to complex structure-activity relationships. Here, we investigated dimerization as a strategy for developing ligands with novel pharmacology. We regioselectively synthesised and systematically studied parallel, antiparallel and N- to C-terminal cyclized homo- and heterodimer constructs of VP, OT and dVDAVP (1-deamino-4-valine-8-d-arginine-VP). All disulfide-linked dimers, except for the head-to-tail cyclized constructs, retained nanomolar potency despite the structural implications of dimerization. Our results support a single chain interaction for receptor activation. Dimer orientation had little impact on activity, except for the dVDAVP homodimers, where an antagonist to agonist switch was observed at the V1aR. This study provides novel insights into the structural requirements of VP/OT receptor activation and spotlights dimerization as a strategy to modulate pharmacology, a concept also frequently observed in nature.

6.
Plant Signal Behav ; 16(3): 1862564, 2021 03 04.
Artigo em Inglês | MEDLINE | ID: mdl-33470154

RESUMO

Global warming has induced higher frequencies of excessively high-temperature weather episodes, which pose damage risk to rice growth and production. Past studies seldom specified how high temperature-induced carbohydrate metabolism disturbances from both source and sink affect rice fertilization and production. Here we discuss the mechanism of heat-triggered damage to rice quality and production through disturbance of carbohydrate generation and consumption under high temperatures. Furthermore, we provide strong evidence from past studies that rice varieties that maintain high photosynthesis and carbohydrate usage efficiencies under high temperatures will suffer less heat-induced damage during reproductive developmental stages. We also discuss the complexity of expressional regulation of rice genes in response to high temperatures, while highlighting the important roles of heat-inducible post-transcriptional regulations of gene expression. Lastly, we predict future directions in heat-tolerant rice breeding and also propose challenges that need to be conquered in the future.


Assuntos
Metabolismo dos Carboidratos/genética , Regulação da Expressão Gênica de Plantas , Temperatura Alta , Oryza/genética , Oryza/metabolismo , Metabolismo Energético/genética , Fatores de Transcrição/metabolismo
7.
Magn Reson Med Sci ; 19(1): 14-20, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-30956273

RESUMO

PURPOSE: To investigate whether the genu of the corpus callosum is involved in patients with clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) type I. METHODS: Twenty-three cases of clinically confirmed MERS I were analyzed retrospectively, and MRI features of the lesion were observed. The apparent diffusion coefficient (ADC) values of the same region of interests in lesions at the splenium and genu of the corpus callosum were measured before and after treatment (i.e., four groups), and the average ADC values were calculated. Paired t-tests were used to compare the ADC values of lesions in the splenium and genu before and after treatment. Independent sample t-tests were used to compare the values in the splenium and genu after treatment. RESULTS: The mean ADC values of the splenium before and after treatment were 0.448 ± 0.124 and 0.790 ± 0.070 × 10-3 mm2/s, respectively, showing significant difference (P < 0.01). The mean ADC values in the genu before and after treatment were 0.783 ± 0.067 and 0.829 ± 0.070 × 10-3 mm2/s, respectively, also showing significant difference (P < 0.01). There was no significant difference in the ADC values between the splenium and genu after treatment (P > 0.05). CONCLUSION: The genu showed a slight restriction in diffusion in the acute stage of type I MERS. After treatment, this diffusion restriction diminished as it typically does in the splenium. Our results indicate that the pathology in MERS extends well beyond the visible lesions.


Assuntos
Corpo Caloso/diagnóstico por imagem , Corpo Caloso/fisiopatologia , Imagem de Difusão por Ressonância Magnética/métodos , Encefalite/diagnóstico por imagem , Encefalite/fisiopatologia , Adolescente , Adulto , Criança , Pré-Escolar , Difusão , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto Jovem
8.
Biosci Rep ; 39(5)2019 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-30910851

RESUMO

Angiogenesis is a vital step during the process of oncogenesis of a lot of tumors, with no exception in bladder cancer. One of the useful strategies for the development of new drugs against cancer is targeting angiogenesis. In the present study, we found that a small-molecule natural product, which belonged to the ß-carboline alkaloid, named harmine, could strongly inhibit tumor angiogenesis thus exhibiting its ideal treatment efficacy in bladder cancer. In vivo study verified that harmine had the effect of inhibition on human bladder tumor xenograft growth. The inhibitory effect of harmine to bladder cancer growth was coordinated by the effects shown on angiogenesis. To further explore the pharmacological activities of harmine, we tested harmine's influence on blood vessel formation and found that harmine effectively blocked the microvessel sprouting in rat aortic ring assay when stimulated by vascular endothelial growth factor (VEGF). Furthermore, harmine inhibited human umbilical vein endothelial cell (HUVEC) proliferation as well as chemotactic motility, and when we treated HUVEC cell with harmine, the formation of capillary-like structures was also restrained. Moreover, harmine induced bladder cancer cell apoptosis through triggering the caspase-dependent apoptotic pathway and the downstream vascular endothelial growth factor receptor 2 (VEGFR2) kinase pathway was down-regulated, thus suppressing tumor development signals. Herein, our study demonstrated that natural product harmine might have potential in curing human bladder tumor because of its pharmacological function on tumor angiogenesis, trigged by VEGFR2 signaling pathways.


Assuntos
Harmina/farmacologia , Neovascularização Patológica/tratamento farmacológico , Neoplasias da Bexiga Urinária/tratamento farmacológico , Fator A de Crescimento do Endotélio Vascular/genética , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/genética , Inibidores da Angiogênese/farmacologia , Animais , Aorta/efeitos dos fármacos , Aorta/patologia , Apoptose/efeitos dos fármacos , Produtos Biológicos/farmacologia , Linhagem Celular Tumoral/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana , Humanos , Camundongos , Neovascularização Patológica/genética , Neovascularização Patológica/patologia , Ratos , Transdução de Sinais/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas/farmacologia , Neoplasias da Bexiga Urinária/genética , Neoplasias da Bexiga Urinária/patologia , Ensaios Antitumorais Modelo de Xenoenxerto
9.
IEEE Trans Image Process ; 27(11): 5449-5463, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28866492

RESUMO

In this paper, we consider an integrated error concealment system for lost color frames and lost depth frames in multiview videos with depths. We first proposed a pixel-based color error-concealment method with the use of depth information. Instead of assuming that the same moving object in consecutive frames has minimal depth difference, as is done in a state-of-the-art method, a more realistic situation in which the same moving object in consecutive frames can be in different depths is considered. In the derived motion vector candidate set, we consider all the candidate motion vectors in the set, and weight the reference pixels by the depth differences to obtain the final recovered pixel. Compared with the two state-of-the-art methods, the proposed method has average peak signal-to-noise ratio gains of up to 8.73 and 3.98 dB, respectively. Second, we proposed an iterative depth frame error-concealment method. The initial recovered depth frame is obtained by depth-image-based rendering from another available view. The holes in the recovered depth frame are then filled in the proposed priority order. Preprocessing methods (depth difference compensation and inconsistent pixel removal) are performed to improve the performance. Compared with a method that uses the available motion vector in a color frame to recover the lost depth pixels, the hybrid motion vector extrapolation method, the inpainting method and the proposed method have gains of up to 4.31, 10.29, and 6.04 dB, respectively. Finally, for the situation in which the color and the depth frames are lost at the same time, our two methods jointly perform better with a gain of up to 7.79 dB.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA