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1.
Int J Biol Macromol ; 147: 453-462, 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31923519

RESUMO

Due to the favorable stability, water solubility and good biocompatibility, carbon dots have attracted much attention. Herein, a novel nitrogen-doping bifunctional carbon dots (N-BCDs) with ultra-highly quantum yield (QYabs = 70.4%) is prepared through microwave-assisted method. 50 µg/mL of N-BCDs emit intense fluorescence in HeLa and GES-1 cells with negligible cytotoxicity. In addition, effective inhibition of N-BCDs to human insulin (HI) fibrillation is observed even at 10:1 (mass ratio of HI: N-BCDs) by ThT fluorescence, CD assay and TEM. N-BCDs prevent HI from fibrillation with prolonged lag time and reduced fluorescent intensity at equilibrium, regardless of the addition time of N-BCDs (HI: N-BCDs = 1:1, mass ratio), which has been rarely reported before. Furthermore, the morphology of final HI fibrils is shorter and thinner in the presence of N-BCDs. Mechanism studies reveal that the enhanced hydrogen bond between HI monomers and N-BCDs inhibits nucleation during the lag stage (Ka: 1.54 × 104 L·mol-1, 298 K), while the accumulation of N-BCDs blocks the growth of profibrils in the elongation stage. To the best of our knowledge, it's the first time to observe the accumulation of N-BCDs around HI profibrils with TEM. Our study provides a new strategy for developing efficient nanoparticle inhibitors for protein fibrillation.

2.
Sheng Li Xue Bao ; 71(6): 809-823, 2019 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-31879736

RESUMO

Spinal α-motoneurons directly innervate skeletal muscles and function as the final common path for movement and behavior. The processes that determine the excitability of motoneurons are critical for the execution of motor behavior. In fact, it has been noted that spinal motoneurons receive various neuromodulatory inputs, especially monoaminergic one. However, the roles of histamine and hypothalamic histaminergic innervation on spinal motoneurons and the underlying ionic mechanisms are still largely unknown. In the present study, by using the method of intracellular recording on rat spinal slices, we found that activation of either H1 or H2 receptor potentiated repetitive firing behavior and increased the excitability of spinal α-motoneurons. Both of blockage of K+ channels and activation of Na+-Ca2+ exchangers were involved in the H1 receptor-mediated excitation on spinal motoneurons, whereas the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels were responsible for the H2 receptor-mediated excitation. The results suggest that, through switching functional status of ion channels and exchangers coupled to histamine receptors, histamine effectively biases the excitability of the spinal α-motoneurons. In this way, the hypothalamospinal histaminergic innervation may directly modulate final motor outputs and actively regulate spinal motor reflexes and motor execution.


Assuntos
Histamina , Neurônios Motores , Animais , Histamina/farmacologia , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/metabolismo , Neurônios Motores/efeitos dos fármacos , Neurônios Motores/fisiologia , Ratos , Receptores Histamínicos H2/metabolismo , Trocador de Sódio e Cálcio/metabolismo
3.
Microbiome ; 7(1): 98, 2019 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-31255176

RESUMO

BACKGROUND: Western-style diets arouse neuroinflammation and impair emotional and cognitive behavior in humans and animals. Our previous study showed that a high-fructose diet caused the hippocampal neuroinflammatory response and neuronal loss in animals, but the underlying mechanisms remained elusive. Here, alterations in the gut microbiota and intestinal epithelial barrier were investigated as the causes of hippocampal neuroinflammation induced by high-fructose diet. RESULTS: A high-fructose diet caused the hippocampal neuroinflammatory response, reactive gliosis, and neuronal loss in C57BL/6N mice. Depletion of the gut microbiota using broad-spectrum antibiotics suppressed the hippocampal neuroinflammatory response in fructose-fed mice, but these animals still exhibited neuronal loss. Gut microbiota compositional alteration, short-chain fatty acids (SCFAs) reduction, intestinal epithelial barrier impairment, NOD-like receptor family pyrin domain-containing 6 (NLRP6) inflammasome dysfunction, high levels of serum endotoxin, and FITC-dextran were observed in fructose-fed mice. Of note, SCFAs, as well as pioglitazone (a selective peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist), shaped the gut microbiota and ameliorated intestinal epithelial barrier impairment and NLRP6 inflammasome dysfunction in fructose-fed mice. Moreover, SCFAs-mediated NLRP6 inflammasome activation was inhibited by histamine (a bacterial metabolite) in ex vivo colonic explants and suppressed in murine CT26 colon carcinoma cells transfected with NLRP6 siRNA. However, pioglitazone and GW9662 (a PPAR-γ antagonist) exerted no impact on SCFAs-mediated NLRP6 inflammasome activation in ex vivo colonic explants, suggesting that SCFAs may stimulate NLRP6 inflammasome independently of PPAR-γ activation. SCFAs and pioglitazone prevented fructose-induced hippocampal neuroinflammatory response and neuronal loss in mice. Additionally, SCFAs activated colonic NLRP6 inflammasome and increased DCX+ newborn neurons in the hippocampal DG of control mice. CONCLUSIONS: Our findings reveal that gut dysbiosis is a critical factor for a high-fructose diet-induced hippocampal neuroinflammation in C57BL/6N mice possibly mediated by impairing intestinal epithelial barrier. Mechanistically, the defective colonic NLRP6 inflammasome is responsible for intestinal epithelial barrier impairment. SCFAs can stimulate NLRP6 inflammasome and ameliorate the impairment of intestinal epithelial barrier, resulting in the protection against a high-fructose diet-induced hippocampal neuroinflammation and neuronal loss. This study addresses a gap in the understanding of neuronal injury associated with Western-style diets. A new intervention strategy for reducing the risk of neurodegenerative diseases through SCFAs supplementation or dietary fiber consumption is emphasized.

4.
Medicine (Baltimore) ; 98(21): e15758, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31124961

RESUMO

BACKGROUND: For cancer, it is common that there is usually a dysregulation of the long noncoding RNA regulator of reprogramming (LncRNA ROR). To illustrate the application of LncRNA ROR, which serves as the prognostic marker for the malignant tumors, it is of great importance to conduct a meta-analysis. METHODS: There were 3 databases being applied. The data used were collected before January 5, 2018. These 3 databases include the OVID, PubMed, and Science databse. To further explore the association between the expression and survival of LncRNA ROR, it calculated the 95% confidence intervals (CIs) and hazard ratios (HRs). Meanwhile, the odds ratios (ORs) have been calculated for the evaluation of the correlation between the pathological and expression parameters of LncRNA ROR. RESULTS: There were 8 researches participated by 720 patients. According to the HR, it has been implied that there was a high LncRNA ROR expression related with the weak disease-free survival (DFS) (HR = 3.48, 95% CI, 2.24-5.41) and overall survival (OS) (HR = 2.47, 95% CI, 1.76-3.47) among the cancer patients with none dramatic heterogeneity. There was also a correlation among lymph node metastasis (OR = 5.38, 95% CI, 2.21-13.12), high tumor stage (OR = 3.80, 95% CI, 1.95-7.41), and larger tumor size (OR = 4.43, 95% CI, 1.26-15.51). CONCLUSIONS: Thus, it can be predicted about the lymph node metastasis and high tumor stage, larger tumor size, DFS, and poor OS based on the high LncRNA ROR. This suggests that high LncRNA ROR can be used as a new indicator of poor prognosis in cancer.


Assuntos
Neoplasias/genética , Neoplasias/patologia , RNA Longo não Codificante/genética , Biomarcadores Tumorais , China , Humanos , Metástase Linfática , Estadiamento de Neoplasias , Análise de Sobrevida , Carga Tumoral
5.
Front Cell Neurosci ; 13: 153, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31105528

RESUMO

Central orexinergic system deficiency results in cataplexy, a motor deficit characterized with a sudden loss of muscle tone, highlighting a direct modulatory role of orexin in motor control. However, the neural mechanisms underlying the regulation of orexin on motor function are still largely unknown. The subthalamic nucleus (STN), the only excitatory structure of the basal ganglia, holds a key position in the basal ganglia circuitry and motor control. Previous study has revealed a wide distribution of orexinergic fibers as well as orexin receptors in the basal ganglia including the STN. Therefore, in the present study, by using whole-cell patch clamp recording and immunostaining techniques, the direct effect of orexin on the STN neurons in brain slices, especially the underlying receptor and ionic mechanisms, were investigated. Our results show that orexin-A elicits an excitatory effect on STN neurons in rats. Tetrodotoxin (TTX) does not block the orexin-induced excitation on STN neurons, suggesting a direct postsynaptic action of the neuropeptide. The orexin-A-induced inward current on STN neurons is mediated by the activation of both OX1 and OX2 receptors. Immunofluorescence result shows that OX1 and OX2 receptors are co-expressed and co-localized in STN neurons. Furthermore, Na+-Ca2+ exchangers (NCXs) and inward rectifier K+ channels co-mediate the excitatory effect of orexin-A on STN neurons. These results demonstrate a dual receptor in conjunction with the downstream ionic mechanisms underlying the excitatory action of orexin on STN neurons, suggesting a potential modulation of the central orexinergic system on basal ganglia circuitry as well as its related motor control and motor diseases.

6.
Neuropeptides ; 76: 101934, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31130301

RESUMO

Corticotropin-releasing factor (CRF) is a neuropeptide mainly synthesized in the hypothalamic paraventricular nucleus and has been traditionally implicated in stress and anxiety. Intriguingly, genetic or pharmacological manipulation of CRF receptors affects locomotor activity as well as motor coordination and balance in rodents, suggesting an active involvement of the central CRFergic system in motor control. Yet little is known about the exact role of CRF in central motor structures and the underlying mechanisms. Therefore, in the present study, we focused on the effect of CRF on the lateral vestibular nucleus (LVN) in the brainstem vestibular nuclear complex, an important center directly contributing to adjustment of muscle tone for both postural maintenance and the alternative change from the extensor to the flexor phase during locomotion. The results show that CRF depolarizes and increases the firing rate of neurons in the LVN. Tetrodotoxin does not block the CRF-induced depolarization and inward current on LVN neurons, suggesting a direct postsynaptic action of the neuropeptide. The CRF-induced depolarization on LVN neurons was partly blocked by antalarmin or antisauvagine-30, selective antagonists for CRF receptors 1 (CRFR1) and 2 (CRFR2), respectively. Furthermore, combined application of antalarmin and antisauvagine-30 totally abolished the CRF-induced depolarization. Immunofluorescence results show that CRFR1 and CRFR2 are co-localized in the rat LVN. These results demonstrate that CRF excites the LVN neurons by co-activation of both CRFR1 and CRFR2, suggesting that via the direct modulation on the LVN, the central CRFergic system may actively participate in the central vestibular-mediated postural and motor control.


Assuntos
Hormônio Liberador da Corticotropina/fisiologia , Neurônios/fisiologia , Receptores de Hormônio Liberador da Corticotropina/fisiologia , Núcleo Vestibular Lateral/fisiologia , Potenciais de Ação/efeitos dos fármacos , Animais , Hormônio Liberador da Corticotropina/administração & dosagem , Feminino , Masculino , Neurônios/efeitos dos fármacos , Ratos Sprague-Dawley , Núcleo Vestibular Lateral/efeitos dos fármacos
8.
J Neurosci ; 39(3): 420-433, 2019 01 16.
Artigo em Inglês | MEDLINE | ID: mdl-30413645

RESUMO

Vestibular compensation is responsible for the spontaneous recovery of postural, locomotor, and oculomotor dysfunctions in patients with peripheral vestibular lesion or posterior circulation stroke. Mechanism investigation of vestibular compensation is of great importance in both facilitating recovery of vestibular function and understanding the postlesion functional plasticity in the adult CNS. Here, we report that postsynaptic histamine H1 receptor contributes greatly to facilitating vestibular compensation. The expression of H1 receptor is restrictedly increased in the ipsilesional rather than contralesional GABAergic projection neurons in the medial vestibular nucleus (MVN), one of the most important centers for vestibular compensation, in unilateral labyrinthectomized male rats. Furthermore, H1 receptor mediates an asymmetric excitation of the commissural GABAergic but not glutamatergic neurons in the ipsilesional MVN, which may help to rebalance bilateral vestibular systems and promote vestibular compensation. Selective blockage of H1 receptor in the MVN significantly retards the recovery of both static and dynamic vestibular symptoms following unilateral labyrinthectomy, and remarkably attenuates the facilitation of betahistine, whose effect has traditionally been attributed to its antagonistic action on the presynaptic H3 receptor, on vestibular compensation. These results reveal a previously unknown role for histamine H1 receptor in vestibular compensation and amelioration of vestibular motor deficits, as well as an involvement of H1 receptor in potential therapeutic effects of betahistine. The findings provide not only a new insight into the postlesion neuronal circuit plasticity and functional recovery in the CNS, but also a novel potential therapeutic target for vestibular disorders.SIGNIFICANCE STATEMENT Vestibular disorders manifest postural imbalance, nystagmus, and vertigo. Vestibular compensation is critical for facilitating recovery from vestibular disorders, and of great importance in understanding the postlesion functional plasticity in the adult CNS. Here, we show that postsynaptic H1 receptor in the medial vestibular nucleus (MVN) contributes greatly to the recovery of both static and dynamic symptoms following unilateral vestibular lesion. H1 receptor selectively mediates the asymmetric activation of commissural inhibitory system in the ipsilesional MVN and actively promotes vestibular compensation. The findings provide not only a new insight into the postlesion neuronal circuit plasticity and functional recovery of CNS, but also a novel potential therapeutic target for promoting vestibular compensation and ameliorating vestibular disorders.


Assuntos
Receptores Histamínicos H1/efeitos dos fármacos , Vestíbulo do Labirinto/fisiopatologia , Animais , beta-Histina/uso terapêutico , Orelha Interna , Lateralidade Funcional/efeitos dos fármacos , Antagonistas dos Receptores Histamínicos H1/farmacologia , Antagonistas dos Receptores Histamínicos H3/uso terapêutico , Locomoção/efeitos dos fármacos , Masculino , Rede Nervosa/efeitos dos fármacos , Rede Nervosa/fisiopatologia , Neurônios/efeitos dos fármacos , Nistagmo Fisiológico/efeitos dos fármacos , Técnicas de Patch-Clamp , Equilíbrio Postural/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Doenças Vestibulares/tratamento farmacológico , Núcleos Vestibulares/citologia , Núcleos Vestibulares/efeitos dos fármacos , Núcleos Vestibulares/fisiopatologia , Ácido gama-Aminobutírico
9.
Mol Psychiatry ; 24(2): 282-293, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30087452

RESUMO

Hypothalamic neuropeptide orexin has been implicated in the pathophysiology of psychiatric disorders and accumulating clinical evidence indicates a potential link between orexin and depression. However, the exact role of orexin in depression, particularly the underlying neural substrates and mechanisms, remains unknown. In this study, we reveal a direct projection from the hypothalamic orexinergic neurons to the ventral pallidum (VP), a structure that receives an increasing attention for its critical position in rewarding processing, stress responses, and depression. We find that orexin directly excites GABAergic VP neurons and prevents depressive-like behaviors in rats. Two orexin receptors, OX1R and OX2R, and their downstream Na+-Ca2+ exchanger and L-type Ca2+ channel co-mediate the effect of orexin. Furthermore, pharmacological blockade or genetic knockdown of orexin receptors in VP increases depressive-like behaviors in forced swim test and sucrose preference test. Intriguingly, blockage of orexinergic inputs in VP has no impact on social proximity in social interaction test between novel partners, but remarkably strengthens social avoidance under an acute psychosocial stress triggered by social rank. Notably, a significantly increased orexin level in VP is accompanied by an increase in serum corticosterone in animals exposed to acute stresses, including forced swimming, food/water deprivation and social rank stress, rather than non-stress situations. These results suggest that endogenous orexinergic modulation on VP is especially critical for protecting against depressive reactions to stressful events. The findings define an indispensable role for the central orexinergic system in preventing depression by promoting stress resilience.


Assuntos
Depressão/tratamento farmacológico , Orexinas/metabolismo , Orexinas/farmacologia , Animais , Comportamento Animal/efeitos dos fármacos , Depressão/fisiopatologia , Modelos Animais de Doenças , Neurônios GABAérgicos/metabolismo , Hipotálamo/metabolismo , Masculino , Neuropeptídeos/metabolismo , Receptores de Orexina/metabolismo , Receptores de Orexina/fisiologia , Ratos , Ratos Sprague-Dawley , Comportamento Social , Estresse Psicológico/metabolismo
10.
J Clin Invest ; 128(12): 5413-5427, 2018 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-30226827

RESUMO

The subthalamic nucleus (STN) is an effective therapeutic target for deep brain stimulation (DBS) for Parkinson's disease (PD), and histamine levels are elevated in the basal ganglia in PD patients. However, the effect of endogenous histaminergic modulation on STN neuronal activities and the neuronal mechanism underlying STN-DBS are unknown. Here, we report that STN neuronal firing patterns are more crucial than firing rates for motor control. Histamine excited STN neurons, but paradoxically ameliorated parkinsonian motor deficits, which we attributed to regularizing firing patterns of STN neurons via the hyperpolarization-activated cyclic nucleotide-gated channel 2 (HCN2) channel coupled to the H2 receptor. Intriguingly, DBS increased histamine release in the STN and regularized STN neuronal firing patterns under parkinsonian conditions. HCN2 contributed to the DBS-induced regularization of neuronal firing patterns, suppression of excessive ß oscillations, and alleviation of motor deficits in PD. The results reveal an indispensable role for regularizing STN neuronal firing patterns in amelioration of parkinsonian motor dysfunction and a functional compensation for histamine in parkinsonian basal ganglia circuitry. The findings provide insights into mechanisms of STN-DBS as well as potential therapeutic targets and STN-DBS strategies for PD.


Assuntos
Ritmo beta , Estimulação Encefálica Profunda , Córtex Motor , Neurônios , Doença de Parkinson Secundária , Núcleo Subtalâmico , Animais , Histamina/metabolismo , Masculino , Córtex Motor/metabolismo , Córtex Motor/patologia , Córtex Motor/fisiopatologia , Neurônios/metabolismo , Neurônios/patologia , Doença de Parkinson Secundária/metabolismo , Doença de Parkinson Secundária/patologia , Doença de Parkinson Secundária/fisiopatologia , Doença de Parkinson Secundária/terapia , Ratos , Ratos Sprague-Dawley , Núcleo Subtalâmico/metabolismo , Núcleo Subtalâmico/patologia , Núcleo Subtalâmico/fisiopatologia
11.
J Thorac Dis ; 10(6): 3196-3205, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30069315

RESUMO

Background: Postoperative pulmonary dysfunction (PPD) is a common complication observed in patients after cardiac surgery with cardiopulmonary bypass (CPB). The underlying mechanism regulating lung injury after CPB is unclear. However, since the involvement of regulatory T (Treg) cells and T helper 17 (Th17) cells in immune responses has been well established, in this study, we investigated the contribution of these lymphocyte subsets to the development of PPD after CPB. Methods: Fifty-six rheumatic heart disease (RHD) patients' blood samples were collected at different time points before and after surgery. The samples were analyzed by flow cytometry to quantify cells and by enzyme-linked immunosorbent assay (ELISA) to measure the cytokine content. In addition, the inhibitory function of Treg cells of ten patients was tested before and after surgery. Results: We showed that a decreased percentage of Treg cells and reduced Treg/Th17 ratio before anesthesia and after neutralization are meaningful predictors of severe PPD (AUC 0.722, 95% CI: 0.557 to 0.888; 0.787, 95% CI: 0.639 to 0.934; 0.751, 95% CI: 0.593 to 0.919; 0.551, 95% CI: 0.366 to 0.735). Interestingly, both the percentage of Treg cells and their suppressive effect on effector T lymphocyte (Teff) cells were increased after CPB, and both effects may play a protective role in PPD. By contrast, severe PPD was associated with increased IL-17A levels. Conclusions: The increased proportion of Treg cells in the CD4+ T cell population and higher ratio of Treg/Th17 before anesthesia induction and 30 min after heparin neutralization can partially protect patients from a severe inflammatory response and PPD.

12.
Neurosci Bull ; 34(6): 1029-1036, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30143981

RESUMO

The ventral pallidum (VP) is a crucial component of the limbic loop of the basal ganglia and participates in the regulation of reward, motivation, and emotion. Although the VP receives afferent inputs from the central histaminergic system, little is known about the effect of histamine on the VP and the underlying receptor mechanism. Here, we showed that histamine, a hypothalamic-derived neuromodulator, directly depolarized and excited the GABAergic VP neurons which comprise a major cell type in the VP and are responsible for encoding cues of incentive salience and reward hedonics. Both postsynaptic histamine H1 and H2 receptors were found to be expressed in the GABAergic VP neurons and co-mediate the excitatory effect of histamine. These results suggested that the central histaminergic system may actively participate in VP-mediated motivational and emotional behaviors via direct modulation of the GABAergic VP neurons. Our findings also have implications for the role of histamine and the central histaminergic system in psychiatric disorders.


Assuntos
Prosencéfalo Basal/citologia , Neurônios GABAérgicos/efeitos dos fármacos , Histamina/farmacologia , Receptores Histamínicos H1/metabolismo , Receptores Histamínicos H2/metabolismo , Potenciais de Ação/efeitos dos fármacos , Animais , Dimaprit/farmacologia , Relação Dose-Resposta a Droga , Estimulação Elétrica , Feminino , Agonistas dos Receptores Histamínicos/farmacologia , Lisina/análogos & derivados , Lisina/metabolismo , Masculino , Técnicas de Patch-Clamp , Piridinas/farmacologia , Ratos , Ratos Sprague-Dawley , Bloqueadores dos Canais de Sódio/farmacologia , Tetrodotoxina/farmacologia , Ácido gama-Aminobutírico/metabolismo
13.
Nanoscale ; 10(33): 15468-15484, 2018 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-29926871

RESUMO

We report a multi-step synthetic method to obtain ultrathin silver nanowires (Ag NWs) from an aqueous solution with a ∼17 nm diameter average, and where some of them decreased down to 9 nm. Carefully designed seed screening processes including LED irradiation at high temperature for a short time, and then continuous H2O2 etching, and relative growth mechanisms of high-yield five-twinned pentagonal seeds and ultrathin Ag NWs in aqueous environment are detailed. Then, a rapid and simple multiphase interfacial assembly method particularly suitable for the separation of ultrathin Ag NWs from various by-products was demonstrated with a clear mechanism explanation. Next, a unique optical interaction between light and individual AG NWs, as well as feature structures in the AG NWs film, was investigated by a micro-domain optical confocal microscope measurement in situ together with a theoretical explanation using modal transmission theory. That revealed that the haze problem of AG NWs films was not only arising from the interaction between light and individual or crossed Ag NWs but was also greatly dependent on a weak coupling effect of leaky modes supported by adjacent Ag NWs with large distances which had not been considered before. We then provided direct experimental evidence and concluded how to obtain haze-free films with 100% transparency in the whole visible range based on ultrathin Ag NWs. This breakthrough in diameter confinement and purification of Ag NWs is a highly expected step to overcome the well-focused light diffusion and absorption problems of Ag NWs-based devices applied in various fields such as flexible electronics, high-clarity displays, visible transparent heaters, photovoltaics and various optoelectronic technologies.

14.
Carbohydr Res ; 457: 1-7, 2018 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-29304441

RESUMO

Two genes encoding the ß-N-acetylhexosaminidases Am2301 and Am2446 were cloned successfully from the mucin-degrading bacterium Akkermansia muciniphila. The recombinant enzymes with molecular masses of 61 kDa and 78 kDa were isolated and biochemically characterised. The optimum temperature of both enzymes was 37 °C, and the optimum pH was determined to be pH 5.0 for Am2301 and pH 6.5 for Am2446. The addition of sodium dodecyl sulphate (SDS) reduced the enzymes' activity significantly. Cu2+-ions decreased the activity of Am2301 by 70%, while the activity of Am2446 was significantly reduced by Fe3+-ions. PugNAc strongly inhibited both enzymes already in the sub-micromolar concentration range. The enzymes catalysed the hydrolysis of ß1,4-linked N-acetylgalactosamine and ß1,6-linked N-acetylglucosamine from glycan standards, as well as ß1,2-linked N-acetylglucosamine units from the non-reducing end of N-glycans. The present study describes the first functional characterisation of ß-N-acetylhexosaminidases from this human gut symbiont.


Assuntos
Glicosídeo Hidrolases/metabolismo , Mucinas/metabolismo , Verrucomicrobia/enzimologia , beta-N-Acetil-Hexosaminidases/metabolismo , Intestinos/microbiologia , Especificidade por Substrato
15.
Appl Opt ; 56(25): 7230-7236, 2017 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-29047990

RESUMO

The integrated polymer optical readout has been recognized as a promising route to obtain miniaturized cantilever-based sensor works on static mode for various liquid-state chemical and biological measurements in portable lab-on-chip systems. For conventional optical readouts based on end-fire coupling mechanisms, the most sensitive region was limited to a cantilever deflection of several micrometers due to the Gaussian profile of the mode in polymer waveguides. We proposed an integrated optical readout based on a hybrid plasmon directional coupler aiming at improving the sensitivity at the sub-micrometer deflection region (<1 µm). The coupler consists of a short-range surface plasmon waveguide and a polymer waveguide. We show that the coupling length and the propagation loss of the coupler are ultra-sensitive to the deflection, which leads to improved sensitivity of the readout. In addition, the dynamic range can be extended by integrating an array of hybrid plasmon directional couplers onto a single microcantilever. The proposed optical readout is beneficial to high sensitivity cantilever-based sensors for lab-on-chip applications and enables the design of more compact optical waveguide-based sensors in water.

16.
Curr Biol ; 27(17): 2661-2669.e5, 2017 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-28844644

RESUMO

Cerebellar ataxia, characterized by motor incoordination, postural instability, and gait abnormality [1-3], greatly affects daily activities and quality of life. Although accumulating genetic and non-genetic etiological factors have been revealed [4-7], effective therapies for cerebellar ataxia are still lacking. Intriguingly, corticotropin-releasing factor (CRF), a peptide hormone and neurotransmitter [8, 9], is considered a putative neurotransmitter in the olivo-cerebellar system [10-14]. Notably, decreased levels of CRF in the inferior olive (IO), the sole origin of cerebellar climbing fibers, have been reported in patients with spinocerebellar degeneration or olivopontocerebellar atrophy [15, 16], yet little is known about the exact role of CRF in cerebellar motor coordination and ataxia. Here we report that deficiency of CRF in the olivo-cerebellar system induces ataxia-like motor abnormalities. CRFergic neurons in the IO project directly to the cerebellar nuclei, the ultimate integration and output node of the cerebellum, and CRF selectively excites glutamatergic projection neurons rather than GABAergic neurons in the cerebellar interpositus nucleus (IN) via two CRF receptors, CRFR1 and CRFR2, and their downstream inward rectifier K+ channel and/or hyperpolarization-activated cyclic nucleotide-gated (HCN) channel. Furthermore, CRF promotes cerebellar motor coordination and rescues ataxic motor deficits. The findings define a previously unknown role for CRF in the olivo-cerebellar system in the control of gait, posture, and motor coordination, and provide new insight into the etiology, pathophysiology, and treatment strategy of cerebellar ataxia.


Assuntos
Ataxia/fisiopatologia , Cerebelo/fisiologia , Hormônio Liberador da Corticotropina/deficiência , Atividade Motora/fisiologia , Animais , Masculino , Neurônios/fisiologia , Ratos , Ratos Sprague-Dawley
17.
Sci Rep ; 7(1): 6813, 2017 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-28754959

RESUMO

One of the main challenges for highly sensitive surface-enhanced Raman scattering (SERS) detection is the noise interference of fluorescence signals arising from the analyte molecules. Here we used three types of gold nanostars (GNSs) SERS probes treated by different surface modification methods to reveal the simultaneously existed Raman scattering enhancement and inhibiting fluorescence behaviors during the SERS detection process. As the distance between the metal nanostructures and the analyte molecules can be well controlled by these three surface modification methods, we demonstrated that the fluorescence signals can be either quenched or enhanced during the detection. We found that fluorescence quenching will occur when analyte molecules are closely contacted to the surface of GNSs, leading to a ~100 fold enhancement of the SERS sensitivity. An optimized Raman signal detection limit, as low as the level of 10-11 M, were achieved when Rhodamine 6 G were used as the analyte. The presented fluorescence-free GNSs SERS substrates with plentiful hot spots and controllable surface plasmon resonance wavelengths, fabricated using a cost-effective self-assembling method, can be very competitive candidates for high-sensitive SERS applications.

18.
Protein Pept Lett ; 24(8): 735-741, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28741460

RESUMO

BACKGROUND: The biocatalytic oxidation of UDP-glucose in the presence of NAD+ is catalyzed by UDP-glucose dehydrogenases. OBJECTIVES: The main objective of this study was the characterization of a UDP-glucose dehydrogenase (AmUGD) from Akkermansia muciniphila, a bacterium originally isolated from human faeces in an anaerobic medium containing gastric mucin as the sole carbon source. METHODS: The biochemical analysis of AmUGD was performed using a plate reader-based assay measuring the reaction by-product NADH. Furthermore, HPLC- and MALDI-ToF-MS- based methods were used for the enzyme characterization. RESULTS: The recombinant form of the protein was expressed in E. coli and the purified enzyme exhibited optimum levels of activity at 37°C and pH 9.0. While the enzyme is active in the absence of metal ions, the presence of Zn2+ ions results in markedly enhanced levels of catalysis. CONCLUSION: This study describes the first characterization of a nucleotide-processing enzyme from A. muciniphila. The ease of expression and purification of this enzyme make it ideal for biotechnological applications such as the enzymatic synthesis of nucleotide sugars, which may in turn be used for the synthesis of complex carbohydrates or glycoconjugates.


Assuntos
Proteínas de Bactérias/metabolismo , NAD/metabolismo , Uridina Difosfato Glucose Desidrogenase/metabolismo , Uridina Difosfato Glucose/metabolismo , Verrucomicrobia/química , Proteínas de Bactérias/genética , Cátions Bivalentes , Clonagem Molecular , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Temperatura Alta , Concentração de Íons de Hidrogênio , Cinética , NAD/química , Plasmídeos/química , Plasmídeos/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Especificidade por Substrato , Uridina Difosfato Glucose/química , Uridina Difosfato Glucose Desidrogenase/genética , Verrucomicrobia/enzimologia , Zinco/química , Zinco/metabolismo
19.
Neurosci Bull ; 33(4): 365-372, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28389870

RESUMO

Orexin, released from the hypothalamus, has been implicated in various basic non-somatic functions including feeding, the sleep-wakefulness cycle, emotion, and cognition. However, the role of orexin in somatic motor control is still little known. Here, using whole-cell patch clamp recording and immunostaining, we investigated the effect and the underlying receptor mechanism of orexin-A on neurons in the globus pallidus internus (GPi), a critical structure in the basal ganglia and an effective target for deep brain stimulation therapy. Our results showed that orexin-A induced direct postsynaptic excitation of GPi neurons in a concentration-dependent manner. The orexin-A-induced excitation was mediated via co-activation of both OX1 and OX2 receptors. Furthermore, the immunostaining results showed that OX1 and OX2 receptors were co-localized in the same GPi neurons. These results suggest that the central orexinergic system actively modulates the motor functions of the basal ganglia via direct innervation on GPi neurons and presumably participates in somatic-non-somatic integration.


Assuntos
Globo Pálido/citologia , Interneurônios/efeitos dos fármacos , Receptores de Orexina/metabolismo , Orexinas/farmacologia , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Animais , Relação Dose-Resposta a Droga , Estimulação Elétrica , Antagonistas de Aminoácidos Excitatórios/farmacologia , Feminino , Técnicas In Vitro , Isoquinolinas/farmacologia , Masculino , Receptores de Orexina/agonistas , Técnicas de Patch-Clamp , Piridazinas/farmacologia , Piridinas/farmacologia , Quinoxalinas/farmacologia , Ratos , Ratos Sprague-Dawley , Bloqueadores dos Canais de Sódio/farmacologia , Tetrodotoxina/farmacologia
20.
Sci Rep ; 7: 41146, 2017 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-28117412

RESUMO

Polarization error and temperature noise are two main limits to the performance of resonant fiber optic gyroscope (RFOG). To overcome these limits, we demonstrated a hybrid resonator consisting of a polymer-based long-range surface plasmon polariton (LRSPP) waveguide coupler and a silica fiber. Single-polarization property of LRSPP waveguide and the offsetting of the opposite thermo-optical characteristics between the polymer-based LRSPP waveguide and the silica fiber can effectively inhibit both the polarization error and the temperature noise of RFOG. The measured resonance spectrum of the hybrid resonator shows the absence of polarization noise. The temperature dependence of wavelength shift (TDWS) of resonator dropped to about 2 pm/°C, or even to 0 pm/°C with optimal structure, which dramatically improves the temperature stability of gyroscope system. In addition, the hybrid resonator also shows tremendous application potential in rate-grade and tactical-grade gyroscopes.

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