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PURPOSE: To explore the mechanism by which Remazolam affects the phenotype and function of astrocytes to improve traumatic brain injury (TBI). METHODS: The oxygen -glucose deprivation/recovery (OGD/R) cell model was constructed to simulate the pathological state of astrocytes in a TBI environment. The viability of astrocytes was measured by CCK-8, and the cytoskeleton changes were observed by Phalloidin- TRITC staining. The expressions of differentiation markers, Cx43 and phosphorylated Cx43 (P-Cx43) of A1/A2 astrocytes were detected by Western blot, and the complement C3 and S100A10 of A1/A2 astrocytes were detected by ELISA. The TBI rat model was established. The water content of brain tissue was measured by dry-wet specific gravity method, the pathological morphology of brain tissue in cortical injury area was observed by HE staining method, ROS was detected by fluorescence quantitative method, Cx43 expression was detected by immunohistochemistry method, and the differentiation markers of A1/A2 astrocytes were detected by immunofluorescence. RESULTS: In the TBI environment, astrocytes showed decreased cell viability, blurred skeleton, and increased expression of Cx43. In TBI rats, the water content of brain tissue increased, the brain tissue in the cortex injury area was seriously damaged, ROS and Cx43 expression were significantly increased, and mainly distributed in A2 astrocytes. Remazolam can reverse the above results after the intervention. CONCLUSION: Remazolam affects the phenotype and function of astrocytes to improve TBI via regulating Cx43, and plays a role in protecting the neurological function of TBI rats.
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Lesões Encefálicas Traumáticas , Conexina 43 , Ratos , Animais , Ratos Sprague-Dawley , Conexina 43/metabolismo , Astrócitos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Lesões Encefálicas Traumáticas/tratamento farmacológico , Lesões Encefálicas Traumáticas/metabolismo , Lesões Encefálicas Traumáticas/patologia , Fenótipo , Antígenos de Diferenciação/metabolismo , Água/metabolismoRESUMO
The limitations of protein-based hydrogels, including their insufficient mechanical properties and restricted biological functions, arise from the highly specific functions of proteins as natural building blocks. A potential solution to overcome these shortcomings is the development of protein-protein hydrogels, which integrate structural and functional proteins. In this study, a protein-protein hydrogel formed by crosslinking bovine serum albumin (BSA) and a genetically engineered intrinsically disordered collagen-like protein (CLP) through AgâS bonding is introduced. The approach involves thiolating lysine residues of BSA and crosslinking CLP with Ag+ ions, utilizing thiolation of BSA and the free-cysteines of CLP. The resulting protein-protein hydrogels exhibit exceptional properties, including notable plasticity, inherent self-healing capabilities, and gel-sol transition in response to redox conditions. In comparison to standalone BSA hydrogels, these protein-protein hydrogels demonstrate enhanced cellular viability, and improved cellular migration. In vivo experiments provide conclusive evidence of accelerated wound healing, observed not only in murine models with streptozotocin (Step)-induced diabetes but also in zebrafish models subjected to UV-burn injuries. Detailed mechanistic insights, combined with assessments of proinflammatory cytokines and the expression of epidermal differentiation-related proteins, robustly validate the protein-protein hydrogel's effectiveness in promoting wound repair.
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Hidrogéis , Soroalbumina Bovina , Cicatrização , Peixe-Zebra , Hidrogéis/química , Hidrogéis/farmacologia , Animais , Cicatrização/efeitos dos fármacos , Soroalbumina Bovina/química , Camundongos , Compostos de Sulfidrila/química , Bovinos , Diabetes Mellitus Experimental , Queimaduras/terapia , Queimaduras/tratamento farmacológico , Movimento Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Colágeno/químicaRESUMO
Surgical instrument segmentation is of great significance to robot-assisted surgery, but the noise caused by reflection, water mist, and motion blur during the surgery as well as the different forms of surgical instruments would greatly increase the difficulty of precise segmentation. A novel method called Branch Aggregation Attention network (BAANet) is proposed to address these challenges, which adopts a lightweight encoder and two designed modules, named Branch Balance Aggregation module (BBA) and Block Attention Fusion module (BAF), for efficient feature localization and denoising. By introducing the unique BBA module, features from multiple branches are balanced and optimized through a combination of addition and multiplication to complement strengths and effectively suppress noise. Furthermore, to fully integrate the contextual information and capture the region of interest, the BAF module is proposed in the decoder, which receives adjacent feature maps from the BBA module and localizes the surgical instruments from both global and local perspectives by utilizing a dual branch attention mechanism. According to the experimental results, the proposed method has the advantage of being lightweight while outperforming the second-best method by 4.03%, 1.53%, and 1.34% in mIoU scores on three challenging surgical instrument datasets, respectively, compared to the existing state-of-the-art methods. Code is available at https://github.com/SWT-1014/BAANet.
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Procedimentos Cirúrgicos Robóticos , Movimento (Física) , Água , Instrumentos Cirúrgicos , Processamento de Imagem Assistida por ComputadorRESUMO
The present review and meta-analysis aimed to summarize the currently available data and to compare the important clinical and functional outcomes in patients with proximal humerus fractures who were treated using deltoid split (DS) or deltopectoral (DP) surgical approaches. The PubMed, EMBASE, Scopus and Cochrane Central Register of Controlled Trials databases were systematically searched for randomized controlled trials or observational studies that reported functional outcome data of patients with fracture of proximal humerus who were surgically treated using DS and DP approaches. A total of 14 studies were included in the present meta-analysis. The duration of surgery [min; weighted mean difference (WMD), -16.44; 95% CI, -(25.25-7.63)], amount of blood loss [ml; WMD, -57.99; 95% CI, -(102.74-13.23)] and time to bone union [weeks WMD, -1.66; 95% CI, -(2.30-1.02)] was comparatively lower in patients that underwent DS. There were no statistically significant differences in the pain and quality of life scores, range of movement and risk of complications between the DS and the DP groups. Patients in the DS group had improved shoulder function and constant shoulder score (CSS) at 3 months post-surgery (WMD, 6.36; 95% CI, 1.06-11.65). No differences were observed between the two groups in terms of CSS and disabilities of the arm, shoulder and hand scores at 12 and 24 months post-operatively. The activity of daily living (ADL) score was significantly improved in the DS group at 3 (WMD, 1.23; 95% CI, 0.40-2.06), 6 (WMD, 0.99; 95% CI, 0.72-1.25) and 12 months (WMD, 0.83; 95% CI, 0.18-1.47) after the surgery. The present results suggested that DS and DP surgical approaches were associated with similar clinical outcomes. The DS approach was associated with certain perioperative benefits, as well as reduced time to bone union, improved shoulder function in the early postoperative period and improved ADL scores. These benefits may be considered while choosing between these two surgical approaches.
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OBJECTIVE: Many related scales have been developed and applied to measure patients' medication adherence, but the research on the psychometric characteristics of the scale still requires further studies. This study aims to provide further validation of the GMAS scale by using Rasch analysis and to make targeted recommendations for scale improvement. METHODS: This is a cross-sectional study using secondary data. 312 Chinese adult patients were recruited from two tertiary hospitals and one community health service center in Tianjin to complete a questionnaire containing the GMAS, from January to June 2020. Participants included to have at least one chronic condition and also have been on medication for more than 3 months, but excluded patients with major life-threatening illnesses (e.g. heart failure, cancer), cognitive impairments preventing clear expression and significant communication difficulties. Rasch analysis was used to explore the psychometric properties of the GMAS scale. Key indicators including unidimensionality, validity and reliability, differential item functioning and degree of fit with Rasch model are validated. RESULTS: After fitting the Rasch model for the first time, 56 samples poorly fitting the model were deleted. The remaining 256 samples were used for Rasch analysis. The results show that GMAS can fit the Rasch model well, which proves that the scale has favourable psychometric characteristics. But some items had differential item functioning in whether patients have comorbidities. CONCLUSION: The GMAS was found to be useful as a screening tool for patients' medication adherence problems reported, except some issues to be addressed for further improvement of the scale.
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Neoplasias , Adulto , Humanos , Psicometria/métodos , Reprodutibilidade dos Testes , Estudos Transversais , Inquéritos e QuestionáriosRESUMO
Graphene quantum dots (GQDs), nanomaterials derived from graphene and carbon dots, are highly stable, soluble, and have exceptional optical properties. Further, they have low toxicity and are excellent vehicles for carrying drugs or fluorescein dyes. Specific forms of GQDs can induce apoptosis and could be used to treat cancers. In this study, three forms of GQDs (GQD (nitrogen:carbon = 1:3), ortho-GQD, and meta-GQD) were screened and tested for their potential to inhibit breast cancer cell (MCF-7, BT-474, MDA-MB-231, and T-47D) growth. All three GQDs decreased cell viability after 72 h of treatment and specifically affected breast cancer cell proliferation. An assay for the expression of apoptotic proteins revealed that p21 and p27 were up-regulated (1.41-fold and 4.75-fold) after treatment. In particular, ortho-GQD-treated cells showed G2/M phase arrest. The GQDs specifically induced apoptosis in estrogen receptor-positive breast cancer cell lines. These results indicate that these GQDs induce apoptosis and G2/M cell cycle arrest in specific breast cancer subtypes and could potentially be used for treating breast cancers.
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Apoptose , Neoplasias da Mama , Grafite , Pontos Quânticos , Feminino , Humanos , Apoptose/efeitos dos fármacos , Neoplasias da Mama/tratamento farmacológico , Pontos de Checagem do Ciclo Celular , Grafite/farmacologia , Grafite/uso terapêuticoRESUMO
Cells constantly respond to environmental changes by modulating gene expression programs. These responses may demand substantial costs and, thus, affect cell growth. Understanding the regulation of these processes represents a key question in biology and biotechnology. Here, we studied the responses to osmotic stress in glucose-limited environments. By analyzing seventeen osmotic stress-induced genes and stress-activated protein kinase Hog1, we found that cells exhibited stronger osmotic gene expression response and larger integral of Hog1 nuclear localization during adaptation to osmotic stress under glucose-limited conditions than under glucose-rich conditions. We proposed and verified that in glucose-limited environment, glycolysis intermediates (representing "reserve flux") were limited, which required cells to express more glycerol-production enzymes for stress adaptation. Consequently, the regulatory mechanism of osmoresponse was derived in the presence and absence of such reserve flux. Further experiments suggested that this reserve flux-dependent stress-defense strategy may be a general principle under nutrient-limited environments.
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To reveal the underlying mechanism of the biological function of multicellular systems, it is important to obtain comprehensive spatial gene expression profiles. Among the emerging single-cell spatial-omics techniques, immunofluorescence (IF)-based iterative multiplexed imaging is a promising approach. However, the conventional method is usually costly, time-consuming, labor-intensive, and has low throughput. Moreover, it has yet to be demonstrated in intact multicellular organisms. Here, we developed an integrated microfluidic system to overcome these challenges for quantitatively measuring multiple protein profiles sequentially in situ in the same Drosophila embryo. We designed an array of hydrodynamic trapping sites to automatically capture over ten Drosophila embryos with orientation selectivity at more than 90% trapping rates. We also optimized the geometry of confinement and the on-chip IF protocol to achieve the same high signal-to-noise ratio as the off-chip traditional IF experiments. Moreover, we developed an efficient de-staining protocol by combining on-chip antibody stripping and fluorophore bleaching. Using the same secondary antibody to sequentially stain different genes, we confirmed that the de-stained genes have no detectable interference with the subsequently stained genes, and the gene expression profiles are preserved after multiple cycles of staining and de-staining processes. This preliminary test shows that our newly developed integrated microfluidic system can be a powerful tool for multiplexed imaging of Drosophila embryos. Our work opens a new avenue to design microfluidic chips for multicellular organisms and single-cell spatial-omics techniques.
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Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas , Animais , Drosophila/genética , Microfluídica , Hidrodinâmica , Expressão GênicaRESUMO
OBJECTIVE: To investigate the clinical effect of dexmedetomidine combined with dezocine in local anesthesia for endoscopic dacryocystorhinostomy (DCR). METHODS: Ninety patients undergoing elective endoscopic DCR were randomly divided into two groups, local anesthesia group (LA group n = 45) and general anesthesia group (GA group, n = 45). These subjects were all American Society of Anesthesiologists (ASA)-Physical Status I-II patients. The changes of mean arterial pressure (MAP) and heart rate (HR) were observed and recorded before anesthesia (T0), after anesthesia (T1), at the beginning of surgery (T2), and at the end of surgery (T3). The visual analogue scale (VAS) score was observed and recorded immediately after awakening from anesthesia and at 1, 2, 6, and 12 h after surgery. Additionally, the occurrence of adverse reactions after surgery and the sedation-agitation scale (SAS) score after awakening were recorded. RESULTS: Compared with the LA group, the MAP and HR of the GA group were significantly lower at T1 and T2, but significantly higher at T3. Local anesthesia was associated with lower VAS score immediately after awakening and at 1, 2, 6, and 12 h after surgery. Also, local anesthesia caused a lower incidence of postoperative agitation, nausea, and vomiting. The SAS score in the LA group was markedly higher than that in the GA group. CONCLUSION: Local anesthesia with dexmedetomidine and dezocine as adjuvants in endoscopic DCR has more stable hemodynamics and reduces the stress response during perioperative period. Also, this anesthesia achieves better postoperative sedation and analgesia effects, reduces postoperative complications, and improves the quality of awakening from anesthesia. Collectively, local anesthesia is a comfortable and safe option for patients with high risks of general anesthesia and those unwilling to receive general anesthesia.
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Synthetic Biology aims to create predictable biological circuits and fully operational biological systems. Although there are methods to create more stable oscillators, such as repressilators, independently controlling the oscillation of reporter genes in terms of their amplitude and period is only on theoretical level. Here, we introduce a new oscillator circuit that can be independently controlled by two inducers in Escherichia coli. Some control components, including σECF11 and NahR, were added to the circuit. By systematically tuning the concentration of the inducers, salicylate and IPTG, the amplitude and period can be modulated independently. Furthermore, we constructed a quantitative model to forecast the regulation results. Under the guidance of the model, the expected oscillation can be regulated by choosing the proper concentration combinations of inducers. In summary, our work achieved independent control of the oscillator circuit, which allows the oscillator to be modularized and used in more complex circuit designs.
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Relógios Biológicos/genética , Redes Reguladoras de Genes/genética , Modelos Genéticos , Biologia Sintética/métodos , Escherichia coli/genética , Genes Reporter/genética , Análise de Célula ÚnicaRESUMO
Sulfidized nanoscale zerovalent iron (SNZVI) with improved reactivity and selectivity has shown great potential for environmental remediation. However, it is unclear if SNZVI could be applied for the remediation of soil washing solution, and how a soil-washing surfactant affects the reactivity and selectivity of SNZVI. Here, we assess the impact of Triton X-100 (TX-100) on the reactivity and selectivity of a sulfidized commercial NZVI toward tetrabromobisphenol A (TBBPA). While sulfidation of NZVI improved its reactivity and electron efficiency toward TBBPA, TX-100 could further improve these promoting effects, which was 8-21 and 4-7 times higher than those without TX-100, respectively, depending on TX-100 concentration. Because TX-100 could induce the solubilization of TBBPA, sorb onto the SNZVI surface, and favor the subsequent sorption and degradation of TBBPA. SNZVI performance for successive treatments of TBBPA contaminated water was also greatly improved by TX-100. Moreover, washing the TBBPA-contaminated soil with TX-100 could efficiently extract the TBBPA, and almost all of the TBBPA in the soil washing solution could be efficiently degraded by SNZVI. These results suggest that TX-100 is a good additive to SNZVI for improving its performance, and SNZVI coupled with TX-100 can be a promising technology for the remediation of TBBPA-contaminated soil.
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Água Subterrânea , Tricloroetileno , Poluentes Químicos da Água , Ferro , Octoxinol , Bifenil Polibromatos , SoloRESUMO
This study was aimed at examining the effect and underlying mechanisms of bilobalide (BB) on hepatic injury in streptozotocin- (STZ-) induced diabetes mellitus (DM) in immature rats. Immature rats (one day old) were randomly divided into five groups: group I, control nondiabetic rats; group II, STZ-induced, untreated diabetic rats; groups III/IV/V, STZ-induced and BB-treated diabetic rats, which were intraperitoneally injected with BB (2.5 mg/kg, 5 mg/kg, or 10 mg/kg) after 3 days followed by STZ treatment. We observed that BB improved the histopathological changes and maintained normal glucose metabolism, blood lipid, and liver function indicators, such as fasting blood glucose, obesity index, HbA1c, HOMA-IR, fast serum insulin, adiponectin, total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), aspartate transaminase (AST), and alanine transaminase (ALT) in STZ-induced DM in immature rats by a biochemical analyzer or ELISA. Meanwhile, Western blot analysis showed that in STZ-induced DM immature rats, BB decreased the expression of apoptosis-related proteins Bax, cleaved caspase-3, and cleaved caspase-9 while enhancing the Bcl-2 expression; BB downregulated the expression of ACC related to fat anabolism, while upregulating the expression of CPT-1 related to fat catabolism. Strikingly, treatment with BB significantly increased the expression of AMPKα1 as well as inhibited HMGB1, TLR4, and p-P65 expression in hepatic tissues of immature DM rats. AMPK inhibitor (compound C, CC) cotreated with BB undermined the protective effect of BB on the liver injury. The results of the present study suggested BB may have a significant role in alleviating liver damage in the STZ-induced immature DM rats.
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Proteínas Quinases Ativadas por AMP/metabolismo , Bilobalídeos/farmacologia , Diabetes Mellitus Experimental/metabolismo , Hepatopatias/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Proteínas de Arabidopsis/metabolismo , Glicemia/efeitos dos fármacos , Proteínas de Ligação a DNA/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , NF-kappa B/metabolismo , Ratos , Ratos Wistar , Receptor 4 Toll-Like/metabolismoRESUMO
The causes and consequences of aging have always been a concern. In recent studies, changes in the stress response capacity of cells during aging were quantitatively analyzed. It was found that aging was accompanied by a decline in response capacity. When the response capacity decreased to a critical value, which we assumed was the internal noise level, the cell soon died. To survive, the response capacity should be, at minimum, sufficiently strong to resist intracellular noise. Here, we discuss the role of stress response capacity in aging and conjecture that lifespan might be extended by enhancing stress response capacity.
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Envelhecimento/genética , Replicação do DNA/genética , Longevidade/genética , Proteínas de Saccharomyces cerevisiae/genética , Envelhecimento/patologia , Regulação Fúngica da Expressão Gênica/genética , Humanos , Saccharomyces cerevisiae/genética , Estresse Fisiológico/genéticaRESUMO
BACKGROUND: Accuracy of CT-derived fractional flow reserve depends on good image quality. Thus, improving image quality during coronary CT angiography (CCTA) is important. OBJECTIVE: To investigate impact of respiratory motion artifact on coronary image quality focusing on vessel diameter and territory during one beat CCTA by a 256-row detector. METHODS: We retrospectively reviewed patients who underwent CCTA under free-breathing (nâ=â100) and breath-holding (nâ=â100), respectively. Coronary image quality is defined as 4-1 from excellent to poor (non-diagnostic) and respiratory motion artifact severity is also scored on a 4-point scale from no artifact to severe artifact. Coronary image quality and respiratory motion artifact severity of all images were evaluated by two radiologists independently. RESULTS: Compared with free-breathing group, the image qualities are significantly higher in per-segment, per-vessel and per-patient levels (Pâ<â0.001) and proportion of segments with excellent image quality also improves significantly (73.6% vs 60.1%, Pâ<â0.001) in breath-holding group. The image quality improvement occurs in medium-sized coronary arterial segments. Coronary image quality improves with respiratory motion artifacts decreasing in both groups, respectively. CONCLUSION: During one heartbeat CCTA, breath-holding is still recommended to improve coronary image quality due to improvement of the image quality in the medium-sized coronary arteries.
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Artefatos , Reserva Fracionada de Fluxo Miocárdico , Angiografia por Tomografia Computadorizada , Angiografia Coronária , Humanos , Movimento (Física) , Estudos Retrospectivos , Sensibilidade e Especificidade , Tomografia Computadorizada por Raios XRESUMO
The aging process is regarded as the progressive loss of physiological integrity, leading to impaired biological functions and the increased vulnerability to death. Among various biological functions, stress response capacity enables cells to alter gene expression patterns and survive when facing internal and external stresses. Here, we explored changes in stress response capacity during the replicative aging of Saccharomyces cerevisiae. To this end, we used a high-throughput microfluidic device to deliver intermittent pulses of osmotic stress and tracked the dynamic changes in the production of downstream stress-responsive proteins, in a large number of individual aging cells. Cells showed a gradual decline in stress response capacity of these osmotic-related downstream proteins during the aging process after the first 5 generations. Among the downstream stress-responsive genes and unrelated genes tested, the residual level of response capacity of Trehalose-6-Phosphate Synthase (TPS2) showed the best correlation with the cell remaining lifespan. By monitor dynamics of the upstream transcription factors and mRNA of Tps2, it was suggested that the decline in downstream stress response capacity was caused by the decline of translational rate of these proteins during aging.
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Glucosiltransferases/genética , Técnicas Analíticas Microfluídicas/instrumentação , Saccharomyces cerevisiae/fisiologia , Fatores de Transcrição/genética , Replicação do DNA , Regulação Fúngica da Expressão Gênica , Ensaios de Triagem em Larga Escala , Osmose , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Estresse Fisiológico , Imagem com Lapso de TempoRESUMO
Reactions between the U-shaped binuclear Cu(I) complex A that bears short metal-metal distances and the cyano-capped monotopic π-conjugated ligands 1-5 that carry gradually bulkier polyaromatic terminal fragments lead to the formation of π-stacked supramolecular assemblies 6-10, respectively, in yields of 50-80 %. These derivatives have been characterized by multinuclear NMR spectroscopic analysis and X-ray diffraction studies. Their solid-state structures show the selective formation of U-shaped supramolecular assemblies in which two monotopic π-conjugated systems present large (6, 7, and 9) or medium (8 and 10) intramolecular πâ overlap, thus revealing π-π interactions. These assemblies self-organize into head-to-tail π-stacked dimers that in turn self-assemble to afford infinite columnar πâ stacks. The nature, extent, and complexity of the intermolecular contacts within the head-to-tail π-stacked dimer depend on the nature of the terminal polyaromatic fragment carried by the cyano-capped monotopic ligand, but it does not alter the result of the self-assembling process. These results demonstrate that the dinuclear molecular clip A that bears short metal-metal distances allows selective supramolecular assembly processes driven by the formation of intra- and intermolecular short π-π interactions in the resulting self-assembled structures; thus, demonstrating that their shape is not only dictated by the symmetry of the building blocks. This approach opens perspectives toward the formation of extended π-stacked columns based on dissymmetrical and functional π-conjugated systems.
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The CBD gene from Trichoderma reesei was cloned into the Corynebacterium glutamicum secretion expression vector pXMJ19-sp, in which green fluorescent protein was inserted to obtain pXMJ19-sp-GFP-CBD. After induced by 0.5 mmol/L IPTG, GFP-CBD was expressed in Corynebacterium glutamicum at high level of 200 mg/L. The GFP-CBD could be purified to high purity with cellulose column. The results indicated CBD can be successfully used in Corynebacterium glutamicum expression system and thus offer an extremely simple, effective and scalable way for production of recombinant proteins.
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Celulases/biossíntese , Celulose/química , Corynebacterium glutamicum/genética , Vetores Genéticos/genética , Proteínas de Fluorescência Verde/metabolismo , Sequência de Bases , Celulases/genética , Celulose/genética , Clonagem Molecular , Corynebacterium glutamicum/metabolismo , Análise Custo-Benefício , Proteínas de Fluorescência Verde/genética , Dados de Sequência Molecular , Engenharia de Proteínas , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/genética , Trichoderma/genéticaRESUMO
Upon reaction with ligands A, 1 and 3 bearing the 2,5-bis(2-pyridyl)phosphole fragment, an unexpected conversion of Cu(II) metal centers to Cu(I) centers is observed affording either bimetallic complexes bearing a bridging phosphane coordination mode or hexametallic metallacycles.
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Treatment of U-shaped, binuclear Cu(I) complexes 1,1' (1, counterion: BF(4)(-); 1', counterion: PF(6)(-)) with metal cyanide linear linkers K[Au(CN)(2)] (3) and Hg(CN)(2) (4) lead to formation of new supramolecular assemblies 5,5' and 6,6', respectively, in good yield. These derivatives have been characterized by NMR spectroscopy, IR, and X-ray diffraction studies. Derivative 5,5' are supramolecular metallacycles in which intramolecular aurophilic interactions between the Au(I) metal centers of the linkers are observed. Derivative 5 crystallizes as a single solid phase, whereas derivative 5' is characterized in the solid state as four different pseudo-polymorphs (5'a-d). Notably in the case of phase 5'd, a dimer of supramolecular metallacycles bounded by intermolecular aurophilic interactions is formed. Conversely, derivatives 6,6' present large structural diversity depending on the nature of the counterion. Derivative 6 is a supramolecular rectangle in which the Hg(II)-Hg(II) metal distance suggests mercurophilic interaction, whereas 6' crystallizes as two different pseudo-polymorphs 6'a,b, that is, a one-dimensional coordination polymer and one oligomer with no short Hg(II)-Hg(II) metal contacts, respectively. In derivatives 6,6', short contacts between the Hg(II) metal centers and fluorine atoms of the counterions are also observed, which may explain the counterion structural dependence of these supramolecular assemblies based on Hg(II) metal cyanide linker. Comparison of the different solid-state structures characterized highlights the importance of weak secondary interactions between the linkers for the formation supramolecular metallacycles from molecular clips 1,1' and suggests the range of energies required for these interactions to form metallacycles and to induce self-aggregation.
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The reaction of U-shaped, bimetallic, Cu(I) complexes, assembled from a heteroditopic pincer, with cyano-capped pi-conjugated linkers gives a straightforward access to pi-stacked metallocyclophanes in good yields. In these assemblies, the pi-walls have an almost face-to-face arrangement. The versatility of this rational supramolecular synthesis is demonstrated with the use of linkers that have nanoscale lengths (up to 27.7 A), different chemical compositions (oligo(para-phenylenevinylene)s OPVs, oligo(phenylene)s, oligo(phenylethynylene)s), and alternative geometries (linear, angular). Linkers that incorporate an internal pyridyne moiety can also be employed. X-ray diffraction studies revealed that the metallocyclophanes based on linear linkers self-organize into infinite pi-stacked columns in the solid state with intermolecular distances of about 3.6 A. This approach, based on coordination-driven self-assembly, provides a novel and rational strategy for the stacking of extended pi-systems in the solid state.