Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 19 de 19
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Front Neurosci ; 18: 1380467, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38826775

RESUMO

Spinal cord injury is a condition affecting the central nervous system, causing different levels of dysfunction below the point of nerve damage. A 50-year-old woman suffered a neck injury as a result of a car accident. After undergoing posterior cervical C3-C6 internal fixation with titanium plates on one side and C7 lamina decompression, the patient, who had been diagnosed with C3-C7 cervical disk herniation and spinal stenosis causing persistent compression of the spinal cord, was transferred to the rehabilitation department. After implementing the combined therapy of Virtual Reality-based arm and leg cycling along with transcutaneous electrical stimulation of the spinal cord, the patients experienced a notable enhancement in both sensory and motor abilities as per the ASIA scores. The patient's anxiety and depression were reduced as measured by the Hamilton Anxiety and Hamilton Depression Tests. As evaluated by the SCIM-III, the patient's self-reliance and capacity to carry out everyday tasks showed ongoing enhancement, leading to the restoration of their functionality. Hence, the use of Virtual Reality-based arm and leg cycling along with transcutaneous electrical spinal cord stimulation has potential to positively impact function in patients with spinal cord injury. However, as this is a case report, the small number of patients and the fact that the intervention was initiated early after the injury, we were unable to separate the recovery due to the intervention from the natural recovery that is known to occur in the initial weeks and months after SCI. Therefore, further randomized controlled trials with a large sample size is necessary.

2.
Heliyon ; 9(11): e21777, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38034675

RESUMO

Glioma is the most common malignant intracranial tumor, accounting for 80 % of all malignant brain tumors. Growing evidence suggests that lncRNAs are involved in the growth, angiogenesis, metastasis, and therapeutic resistance in a variety of tumors, including glioma. In this study, lncBIRC3-OT (NONHSAT159592.1), which is highly expressed in glioma, was screened by RNA-seq method and verified by quantitative reverse transcription polymerase chain reaction. Subsequently, we knocked down the endogenous expression of lncBIRC3-OT in U87 and U251 cells and found that down-regulated lncBIRC3-OT inhibited cell proliferation, colony formation, migration, and invasion. Mechanically, lncBIRC3-OT could guide RELA protein to the stanniocalcin-1 (STC1) promoter, initiate STC1 transcription, and ultimately promote the progression of glioma. Together, these findings suggest that lncBIRC3-OT is an important regulator promoting glioma progression, and may be a promising therapeutic target for glioma.

3.
Metab Brain Dis ; 38(7): 2289-2300, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37389689

RESUMO

Evidence suggests that non-coding RNAs have a role in glioblastoma multiforme (GBM), although the regulatory mechanisms controlled by competing endogenous RNAs (ceRNAs) in GBM are still poorly understood and infrequently described. This research extensively analyzed circRNA, lncRNA, miRNA, and mRNA expression changes in GBM patients. RNA-sequencing analyses were conducted to investigate differentially expressed genes (DEGs), lncRNAs (DELs), miRNAs (DEMs), and circRNAs (DECs) in the GBM. In this study, researchers found that GBM patients and healthy controls differed in the presence of 1224 DECs, 1406 DELs, 229 DEMs, and 2740 DEGs. PPI network analysis demonstrated that CEACAM5, CXCL17, FAM83A, TMPRSS4, and GGPRC5A were hub genes and enriched in modules. Then a ceRNA network was constructed with 8 circRNA, 7 lncRNAs, 16 miRNAs, and 17 mRNAs. Overall, the ceRNA interaction axes that were found may prove to be pivotal therapeutic targets for treating GBM.


Assuntos
Glioblastoma , MicroRNAs , RNA Longo não Codificante , Humanos , MicroRNAs/genética , MicroRNAs/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Circular/genética , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , Glioblastoma/genética , Redes Reguladoras de Genes , Biologia Computacional , Proteínas de Neoplasias/genética
4.
Hum Cell ; 36(4): 1416-1428, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37162645

RESUMO

Neuropathic pain is a refractory disease with limited treatment options due to its complex mechanisms. Whereas erythropoietin-producing hepatocyte A1 (EphA1) mediates the production of inflammatory factors that are important in the progression of neurological diseases, its role and molecular mechanisms in neuropathic pain remain unclear. In the present study, we established a mouse model of chronic constriction injury (CCI). EphA1 expression was observed to be progressively upregulated at the mRNA and protein levels with the progression of the disease. Subsequently, knockdown of EphA1 expression levels using adenovirus short hairpin RNA (AAV-shEphA1) revealed an increase in mechanical stimulation withdrawal threshold (PWT) and withdrawal latency (PWL) when EphA1 expression was decreased, accompanied by improved dorsal root ganglion injury, increased leukocytosis, decreased microglia, and decreased levels of pro-inflammatory factors. For the underlying mechanism, it was found that EphA1 regulates the activity of the RhoA/ROCK2 pathway by modulating the level of CXCR4. Inhibition of CXCR4 and RhoA/ROCK2 could effectively alleviate the promoting effect of EphA1 upregulation on neuropathic pain. In conclusion, our study suggests that depletion of EphA1 ameliorates neuropathic pain by modulating the CXCR4/RhoA/ROCK2 signaling pathway, and targeting EphA1 may be a potential clinical treatment for neuropathic pain.


Assuntos
Eritropoetina , Neuralgia , Ratos , Camundongos , Animais , Ratos Sprague-Dawley , Neuralgia/genética , Neuralgia/terapia , Transdução de Sinais/fisiologia , Microglia/metabolismo , Eritropoetina/metabolismo , Quinases Associadas a rho/genética
5.
Front Pharmacol ; 14: 1148814, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37025486

RESUMO

Background: Non-alcoholic fatty liver disease (NAFLD) is a chronic advanced liver disease that is highly related to metabolic disorders and induced by a high-fat diet (HFD). Recently, epigallocatechin gallate (EGCG) has been regarded as a protective bioactive polyphenol in green tea that has the ability to protect against non-alcoholic fatty liver disease, but the molecular mechanism remains poorly deciphered. Ferroptosis plays a vital role in the progression of non-alcoholic fatty liver disease, but experimental evidence of ferroptosis inhibition by epigallocatechin gallate is limited. Hence, our study aimed to investigate the effect and mechanisms of epigallocatechin gallate on hepatic ferroptosis to mitigate hepatic injury in high-fat diet-fed mice. Methods: Fifty male C57BL/6 mice were fed either a standard chow diet (SCD), a high-fat diet, or a high-fat diet and administered epigallocatechin gallate or ferrostatin-1 (a ferroptosis-specific inhibitor) for 12 weeks. Liver injury, lipid accumulation, hepatic steatosis, oxidative stress, iron overload, and ferroptosis marker proteins were examined. In vitro, steatotic L-02 cells were used to explore the underlying mechanism. Results: In our research, we found that epigallocatechin gallate notably alleviated liver injury and lipid accumulation, oxidative stress, hepatic steatosis, decreased iron overload and inhibited ferroptosis in a high-fat diet-induced murine model of non-alcoholic fatty liver disease. In vitro experiments, using ferrostatin-1 and a mitochondrial reactive oxygen species (MtROS) scavenger (Mito-TEMPO), we found that epigallocatechin gallate remarkably alleviated oxidative stress and inhibited ferroptosis by reducing the level of mitochondrial reactive oxygen species in steatotic L-02 cells. Conclusion: Taken together, our results revealed that epigallocatechin gallate may exert protective effects on hepatic lipotoxicity by inhibiting mitochondrial reactive oxygen species-mediated hepatic ferroptosis. Findings from our study provide new insight into prevention and treatment strategies for non-alcoholic fatty liver disease pathological processes.

6.
Artigo em Inglês | MEDLINE | ID: mdl-37027668

RESUMO

Studies have shown that percutaneous nerve stimulation can promote repair of ulnar neuropathy. However, this approach requires further optimization. We evaluated multielectrode array-based percutaneous nerve stimulation for treatment of ulnar nerve injury. The optimal stimulation protocol was determined using a multi-layer model of the human forearm using the finite element method. We optimized the number and distance between electrodes, and used ultrasound to aid in electrode placement. Six electrical needles in series along the injured nerve at alternating distances of five and seven centimeters. We validated the model in a clinical trial. Twenty-seven patients were randomly assigned to a control group (CN) and an electrical stimulation with finite element group (FES). The results showed that disability of arm shoulder and hand (DASH) scores decreased and grip strength increased to a greater extent in the FES group than those in the CN group following treatment (P<0.05). Furthermore, the amplitudes of compound motor action potentials (cMAPs) and sensory nerve action potentials (SNAPs) improved in the FES group to a greater extent than those in the CN group. The results showed that our intervention improved hand function and muscle strength, and aided in neurologic recovery, as shown using electromyography. Analysis of blood samples indicated that our intervention may have promoted conversion of the precursor form of brain-derived neurotrophic factor (pro-BDNF) to mature brain-derived neurotrophic factor (BDNF) to promote nerve regeneration. Our percutaneous nerve stimulation regimen for ulnar nerve injury has potential to become a standard treatment option.

7.
Neural Regen Res ; 18(3): 683-688, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36018194

RESUMO

Percutaneous electrical nerve stimulation of an injured nerve can promote and accelerate peripheral nerve regeneration and improve function. When performing acupuncture and moxibustion, locating the injured nerve using ultrasound before percutaneous nerve stimulation can help prevent further injury to an already injured nerve. However, stimulation parameters have not been standardized. In this study, we constructed a multi-layer human forearm model using finite element modeling. Taking current density and activated function as optimization indicators, the optimal percutaneous nerve stimulation parameters were established. The optimal parameters were parallel placement located 3 cm apart with the injury site at the midpoint between the needles. To validate the efficacy of this regimen, we performed a randomized controlled trial in 23 patients with median nerve transection who underwent neurorrhaphy. Patients who received conventional rehabilitation combined with percutaneous electrical nerve stimulation experienced greater improvement in sensory function, motor function, and grip strength than those who received conventional rehabilitation combined with transcutaneous electrical nerve stimulation. These findings suggest that the percutaneous electrical nerve stimulation regimen established in this study can improve global median nerve function in patients with median nerve transection.

8.
Open Life Sci ; 17(1): 1208-1216, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36185409

RESUMO

Time-related cognitive function refers to the capacity of the brain to store, extract, and process specific information. Previous studies demonstrated that the cerebellar cortex participates in advanced cognitive functions, but the role of the cerebellar cortex in cognitive functions is unclear. We established a behavioral model using classical eyeblink conditioning to study the role of the cerebellar cortex in associative learning and memory and the underlying mechanisms. We performed an investigation to determine whether eyeblink conditioning could be established by placing the stimulating electrode in the middle cerebellar peduncle. Behavior training was performed using a microcurrent pulse as a conditioned stimulus to stimulate the middle cerebellar peduncle and corneal blow as an unconditioned stimulus. After 10 consecutive days of training, a conditioned response was successfully achieved in the Delay, Trace-200-ms, and Trace-300-ms groups of guinea pigs, with acquisition rates of >60%, but the Trace-400-ms and control groups did not achieve a conditioned stimulus-related blink conditioned response. It could be a good model for studying the function of the cerebellum during the establishment of eyeblink conditioning.

9.
Front Neurol ; 13: 903207, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36090881

RESUMO

Introduction: Spinal cord injury causes permanent neurological deficits, which have devastating physical, social, and vocational consequences for patients and their families. Traditional Chinese medicine uses acupuncture to treat neuropathic pain and improve nerve conduction velocity. This treatment can also reduce peripheral nerve injury joint contracture and muscle atrophy in affected patients. And it's got a remarkable restoration when electrical stimulation therapy on impaired peripheral nerves in animal models and clinical trials. Case description: A 48-year-old woman was hit by a heavy object that injured her lower back. The patient had a T12-L1 vertebral flexion and stretch fracture with traumatic spinal stenosis. The patient was transferred to the rehabilitation department after posterior T12-L2-segment pedicle screw system distraction and reduction, internal fixation, decompression, and bone graft fusion. Ultrasound-guided electroacupuncture was used to stimulate the sacral nerve, the spinal nerve, and the head of the patient, accompanied by spinal joint loosening training, respiratory training, lumbar comprehensive sports training, paraplegic limbs comprehensive training, and other manipulative treatment. Outcomes: After the intervention, the patient showed significant improvements in sensory and motor scores, resulting in functional recovery according to ASIA and FIM. The patient gradually showed reasonable functional remission. Discussion: The sacral nerve, the spinal cord, and the head were electrically stimulated by ultrasound-guided electroacupuncture in terms of intervention, and various functions of the patient were alleviated to a certain extent. The efficacy of ultrasound-guided electroacupuncture stimulation in treating neurologic symptoms should be validated in future clinical trials.

10.
Neural Regen Res ; 17(10): 2185-2193, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35259827

RESUMO

Previous studies on the mechanisms of peripheral nerve injury (PNI) have mainly focused on the pathophysiological changes within a single injury site. However, recent studies have indicated that within the central nervous system, PNI can lead to changes in both injury sites and target organs at the cellular and molecular levels. Therefore, the basic mechanisms of PNI have not been comprehensively understood. Although electrical stimulation was found to promote axonal regeneration and functional rehabilitation after PNI, as well as to alleviate neuropathic pain, the specific mechanisms of successful PNI treatment are unclear. We summarize and discuss the basic mechanisms of PNI and of treatment via electrical stimulation. After PNI, activity in the central nervous system (spinal cord) is altered, which can limit regeneration of the damaged nerve. For example, cell apoptosis and synaptic stripping in the anterior horn of the spinal cord can reduce the speed of nerve regeneration. The pathological changes in the posterior horn of the spinal cord can modulate sensory abnormalities after PNI. This can be observed in cases of ectopic discharge of the dorsal root ganglion leading to increased pain signal transmission. The injured site of the peripheral nerve is also an important factor affecting post-PNI repair. After PNI, the proximal end of the injured site sends out axial buds to innervate both the skin and muscle at the injury site. A slow speed of axon regeneration leads to low nerve regeneration. Therefore, it can take a long time for the proximal nerve to reinnervate the skin and muscle at the injured site. From the perspective of target organs, long-term denervation can cause atrophy of the corresponding skeletal muscle, which leads to abnormal sensory perception and hyperalgesia, and finally, the loss of target organ function. The mechanisms underlying the use of electrical stimulation to treat PNI include the inhibition of synaptic stripping, addressing the excessive excitability of the dorsal root ganglion, alleviating neuropathic pain, improving neurological function, and accelerating nerve regeneration. Electrical stimulation of target organs can reduce the atrophy of denervated skeletal muscle and promote the recovery of sensory function. Findings from the included studies confirm that after PNI, a series of physiological and pathological changes occur in the spinal cord, injury site, and target organs, leading to dysfunction. Electrical stimulation may address the pathophysiological changes mentioned above, thus promoting nerve regeneration and ameliorating dysfunction.

11.
Acta Neurobiol Exp (Wars) ; 82(4): 468-476, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36748970

RESUMO

Neuropathic pain is associated with nervous system injury and the production of pro­inflammatory factors. Critical functions for ubiquitin­specific peptidase 53 (USP53) have been demonstrated in various diseases. However, the role and mechanism of USP53 in chronic constriction injury (CCI)­induced neuropathic remains unclear. In our current study, a model of neuropathic pain was induced by CCI in rats. Quantitative reverse transcription­polymerase chain reaction (qRT­PCR) and western blotting results demonstrated that USP53 was significantly up­regulated in CCI rats. In addition, silencing of USP53 alleviated neuropathic pain and reduced the production of pro­inflammatory factors in CCI rats according to paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) tests and enzyme­linked immunosorbent assay (ELISA), respectively. Moreover, knockdown of USP53 inhibited the activation of FK506­binding protein 51 (FKBP51)/RhoA/ROCK signaling in CCI rats. In summary, this study revealed that USP53 exacerbated CCI­induced neuropathic pain, potentially via regulation of the FKBP51/RhoA/ROCK pathway.


Assuntos
Neuralgia , Proteases Específicas de Ubiquitina , Animais , Ratos , Constrição , Neuralgia/induzido quimicamente , Neuralgia/metabolismo , Ratos Sprague-Dawley , Transdução de Sinais/fisiologia , Proteases Específicas de Ubiquitina/metabolismo , Quinases Associadas a rho
12.
BMC Plant Biol ; 21(1): 389, 2021 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-34416857

RESUMO

Blueberry (Vaccinium ssp.) is a perennial shrub belonging to the family Ericaceae, which is highly tolerant of acid soils and heavy metal pollution. In the present study, blueberry was subjected to cadmium (Cd) stress in simulated pot culture. The transcriptomics and rhizosphere fungal diversity of blueberry were analyzed, and the iron (Fe), manganese (Mn), copper (Cu), zinc (Zn) and cadmium (Cd) content of blueberry tissues, soil and DGT was determined. A correlation analysis was also performed. A total of 84 374 annotated genes were identified in the root, stem, leaf and fruit tissue of blueberry, of which 3370 were DEGs, and in stem tissue, of which 2521 were DEGs. The annotation data showed that these DEGs were mainly concentrated in a series of metabolic pathways related to signal transduction, defense and the plant-pathogen response. Blueberry transferred excess Cd from the root to the stem for storage, and the highest levels of Cd were found in stem tissue, consistent with the results of transcriptome analysis, while the lowest Cd concentration occurred in the fruit, Cd also inhibited the absorption of other metal elements by blueberry. A series of genes related to Cd regulation were screened by analyzing the correlation between heavy metal content and transcriptome results. The roots of blueberry rely on mycorrhiza to absorb nutrients from the soil. The presence of Cd has a significant effect on the microbial community composition of the blueberry rhizosphere. The fungal family Coniochaetaceae, which is extremely extremelytolerant, has gradually become the dominant population. The results of this study increase our understanding of the plant regulation mechanism for heavy metals, and suggest potential methods of soil remediation using blueberry.


Assuntos
Mirtilos Azuis (Planta)/química , Mirtilos Azuis (Planta)/genética , Mirtilos Azuis (Planta)/microbiologia , Cádmio/efeitos adversos , Micorrizas/genética , Raízes de Plantas/microbiologia , Raízes de Plantas/fisiologia , Adaptação Fisiológica/genética , Biodiversidade , Mirtilos Azuis (Planta)/fisiologia , Cádmio/análise , Cobre/análise , Produtos Agrícolas/química , Produtos Agrícolas/genética , Produtos Agrícolas/microbiologia , Produtos Agrícolas/fisiologia , Perfilação da Expressão Gênica , Ferro/análise , Magnésio/análise , Micorrizas/fisiologia , Rizosfera , Transcriptoma , Zinco/análise
13.
Adv Sci (Weinh) ; 7(15): 2000960, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32775168

RESUMO

The ever increasing library of materials systems developed for organic solar-cells, including highly promising non-fullerene acceptors and new, high-efficiency donor polymers, demands the development of methodologies that i) allow fast screening of a large number of donor:acceptor combinations prior to device fabrication and ii) permit rapid elucidation of how processing affects the final morphology/microstructure of the device active layers. Efficient, fast screening will ensure that important materials combinations are not missed; it will accelerate the technological development of this alternative solar-cell platform toward larger-area production; and it will permit understanding of the structural changes that may occur in the active layer over time. Using the relatively high-efficiency poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3'''-di(2-octyldodecyl)-2,2';5',2'';5'',2'''-quaterthiophen-5,5'''-diyl)] (PCE11):phenyl-C61-butyric acid-methyl-ester acceptor (PCBM) blend systems, it is demonstrated that by means of straight-forward thermal analysis, vapor-phase-infiltration imaging, and transient-absorption spectroscopy, various blend compositions and processing methodologies can be rapidly screened, information on promising combinations can be obtained, reliability issues with respect to reproducibility of thin-film formation can be identified, and insights into how processing aids, such as nucleating agents, affect structure formation, can be gained.

14.
Biosci Rep ; 38(3)2018 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-29051391

RESUMO

Synaptic plasticity plays a role during trace eyeblink conditioning (TEBC). Synaptophysin (Syn) is a major integral transmembrane protein, located particularly in the synaptic vesicles, and is considered a molecular marker of synapses. In addition, Syn immunoreactivity is an important indicator of synaptic plasticity. In the present study, we used immunohistochemical techniques to assess changes in Syn expression in the cerebellar interpositus nucleus (IN) of guinea pigs exposed to TEBC and pseudoconditioning. Additionally, we analyzed the relationship between Syn immunoreactivity and the percentage of trace-conditioned responses. Guinea pigs underwent trace conditioning or pseudoconditioning. Following two, six, or ten sessions, they were perfused and the cerebellum was removed for Syn immunohistochemical evaluation. After sessions 6 and 10, a significant increase in conditioned response (CR) percentage was observed in the trace-conditioned group, with the CR percentage reaching the learning criteria following session 10. Besides, for trace-conditioned animals, the Syn expression in IN was found significantly up-regulated after session 10 compared with pseudoconditioned ones. Our data suggest that the increase in Syn expression links to synaptic plasticity changes in the cerebellar IN and provides a histological substrate in the IN relating to TEBC training. The changing trend of Syn immunoreactivity in the IN is associated with CR percentage.


Assuntos
Condicionamento Palpebral/fisiologia , Plasticidade Neuronal/genética , Sinapses/genética , Sinaptofisina/genética , Animais , Núcleos Cerebelares/metabolismo , Núcleos Cerebelares/fisiologia , Cerebelo/metabolismo , Cerebelo/fisiologia , Regulação da Expressão Gênica , Cobaias , Plasticidade Neuronal/imunologia , Sinapses/imunologia , Sinaptofisina/imunologia
15.
ACS Nano ; 11(7): 6661-6671, 2017 07 25.
Artigo em Inglês | MEDLINE | ID: mdl-28582613

RESUMO

The structural integrity of red blood cells and drug delivery carriers through blood vessels is dependent upon their ability to adapt their shape during their transportation. Our goal is to examine the role of the composition of bio-inspired multicomponent and hairy vesicles on their shape during their transport through in a channel. Through the dissipative particle dynamics simulation technique, we apply Poiseuille flow in a cylindrical channel. We investigate the effect of flow conditions and concentration of key molecular components on the shape, phase separation, and structural integrity of the bio-inspired multicomponent and hairy vesicles. Our results show the Reynolds number and molecular composition of the vesicles impact their flow-induced deformation, phase separation on the outer monolayer due to the Marangoni effect, and rupture. The findings from this study could be used to enhance the design of drug delivery and tissue engineering systems.


Assuntos
1,2-Dipalmitoilfosfatidilcolina/química , Materiais Biomiméticos/química , Dimiristoilfosfatidilcolina/química , Portadores de Fármacos/química , Transição de Fase , Polietilenoglicóis/química , Forma Celular , Colesterol/química , Simulação por Computador , Eritrócitos/química , Eritrócitos/citologia , Glicolipídeos/química , Hidrodinâmica , Lipossomos/química , Modelos Moleculares
16.
ACS Nano ; 10(8): 7351-61, 2016 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-27434532

RESUMO

We examine the interaction between peptide-inspired nanoparticles, or nanopins, and multicomponent vesicles using the dissipative particle dynamics simulation technique. We study the role of nanopin architecture and cholesterol concentration on the binding of the nanopins to the lipid bilayer, their insertion, and postembedding self-organization. We find the insertion to be triggered by enthalpically unfavorable interactions between the hydrophilic solvent and the lipophilic components of the nanopins. The nanopins are observed to form aggregates in solution, insert into the bilayer, and disassemble into the individual nanopins following the insertion process. We examine factors that influence the orientation of the nanopins in the host vesicle. We report the length of the hydrophilic segment of the nanopins to regulate their orientation within the clusters before the embedding process and in the bilayer, after the postinsertion disassembly of the aggregates. The orientation angle distribution for a given nanopin architecture is found to be driven by energy minimization. In addition, higher concentration of cholesterol is observed to constrain the orientation of the nanopins. We also report thermal fluctuations to induce transverse diffusion of nanopins with specific architectures. The incidence of transverse diffusion is observed to decrease with the concentration of cholesterol. Our results can provide guidelines for designing peptide-inspired nanoparticles or macromolecules that can interface with living cells to serve as sensors for applications in medicine, sustainability, and energy.


Assuntos
Anti-Infecciosos , Nanopartículas , Peptídeos , Difusão , Bicamadas Lipídicas
17.
J Phys Chem B ; 120(15): 3666-76, 2016 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-27031284

RESUMO

The dissipative particle dynamics (DPD) simulation technique is a coarse-grained (CG) molecular dynamics-based approach that can effectively capture the hydrodynamics of complex systems while retaining essential information about the structural properties of the molecular species. An advantageous feature of DPD is that it utilizes soft repulsive interactions between the beads, which are CG representation of groups of atoms or molecules. In this study, we used the DPD simulation technique to study the aggregation characteristics of ABA triblock copolymers in aqueous medium. Pluronic polymers (PEG-PPO-PEG) were modeled as two segments of hydrophilic beads and one segment of hydrophobic beads. Tyrosine-derived PEG5K-b-oligo(desaminotyrosyl tyrosine octyl ester-suberate)-b-PEG5K (PEG5K-oligo(DTO-SA)-PEG5K) block copolymers possess alternate rigid and flexible components along the hydrophobic oligo(DTO-SA) chain, and were modeled as two segments of hydrophilic beads and one segment of hydrophobic, alternate soft and hard beads. The formation, structure, and morphology of the initial aggregation of the polymer molecules in aqueous medium were investigated by following the aggregation dynamics. The dimensions of the aggregates predicted by the computational approach were in good agreement with corresponding results from experiments, for the Pluronic and PEG5K-oligo(DTO-SA)-PEG5K block copolymers. In addition, DPD simulations were utilized to determine the critical aggregation concentration (CAC), which was compared with corresponding results from an experimental approach. For Pluronic polymers F68, F88, F108, and F127, the computational results agreed well with experimental measurements of the CAC measurements. For PEG5K-b-oligo(DTO-SA)-b-PEG5K block polymers, the complexity in polymer structure made it difficult to directly determine their CAC values via the CG scheme. Therefore, we determined CAC values of a series of triblock copolymers with 3-8 DTO-SA units using DPD simulations, and used these results to predict the CAC values of triblock copolymers with higher molecular weights by extrapolation. In parallel, a PEG5K-b-oligo(DTO-SA)-b-PEG5K block copolymer was synthesized, and the CAC value was determined experimentally using the pyrene method. The experimental CAC value agreed well with the CAC value predicted by simulation. These results validate our CG models, and demonstrate an avenue to simulate and predict aggregation characteristics of ABA amphiphilic triblock copolymers with complex structures.


Assuntos
Simulação de Dinâmica Molecular , Polímeros/química , Interações Hidrofóbicas e Hidrofílicas , Polímeros/síntese química , Pirenos/química , Água/química
18.
Behav Brain Res ; 264: 82-90, 2014 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-24525424

RESUMO

Defect of autophagy is common to many neurodegenerative disorders because it serves as a major degradation pathway for the clearance of various aggregate-prone proteins. Mammalian target of rapamycin (mTOR) signaling, which is recognized as the most important negative regulator of autophagy, is also involved in neurodegenerative diseases. However, the role of mTOR and its dependent autophagy in normal brain during aging remains unknown. Furthermore, caloric restriction (CR) is frequently used as a tool to study mechanisms behind aging and age-associated diseases because CR can prevent age-related diseases and prolong lifespan in several model organisms. Inhibiting mTOR and promoting autophagy activity play roles in aging delayed by CR. However, whether CR can ameliorate age-related cognition deficits by inhibiting mTOR and activate autophagy in hippocampus needs to be further investigated. Here we showed a decline of autophagic degradation in mice hippocampus in correlation with age-dependent cognitive dysfunction, whereas the activity of mTOR and its upstream brain-derived neurotrophic factor (BDNF)/phosphatidylinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling was decreased with aging. In addition, facilitating the mTOR pathway successfully declines and sustains autophagic degradation with aging in hippocampus by CR treatment and is involved in CR by ameliorating age-related cognitive deficits.


Assuntos
Envelhecimento , Autofagia/fisiologia , Encéfalo/metabolismo , Restrição Calórica/métodos , Transtornos Cognitivos/terapia , Sirolimo/metabolismo , Fatores Etários , Animais , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Transtornos Cognitivos/dietoterapia , Modelos Animais de Doenças , Privação de Alimentos , Regulação da Expressão Gênica , Masculino , Aprendizagem em Labirinto , Camundongos , Camundongos Endogâmicos C57BL , Fosfatidilinositol 3-Quinase/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Fatores de Tempo
19.
Acta Crystallogr Sect E Struct Rep Online ; 66(Pt 10): o2647, 2010 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-21587618

RESUMO

IN THE CRYSTAL STRUCTURE OF THE TITLE COMPOUND [SYSTEMATIC NAME: 1-(2-hy-droxy-eth-yl)-2-methyl-5-nitro-1H-imidazol-3-ium perchlorate], C(6)H(10)N(3)O(3) (+)·ClO(4) (-), the cations are linked by inter-molecular N-H⋯O hydrogen bonds into zigzag chains along the c axis. The cations and anions are connected by O-H⋯O and C-H⋯O hydrogen bonds. A weak intra-molecular C-H⋯O hydrogen bond is also observed.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...