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1.
J Sep Sci ; 2020 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-32388927

RESUMO

In this study, a solid-phase extraction - LC-MS/MS method was developed to determine the degree of glycosylation of glycosylation sites and the ratio of free carrier protein to total carrier protein for glycoconjugate vaccines. To remove and enrich the glycosylated peptides, a solid-phase extraction method was developed, optimized and hyphenated to LC-MS/MS. The developed solid-phase extraction- LC-MS/MS method was shown to possess a wide linear dynamic range (0.03-100 µg/mL), a high sensitivity (0.03 µg/mL for CRM197), good inter-day and intra-day precision (relative standard deviation of peak area <3.3%) and good recoveries from vaccine matrix (90%-105%). Finally, the method was utilized to determine the degree of glycosylation and free carrier protein to total carrier protein ratio for pneumococcal conjugate vaccines and meningococcal vaccines. For quality evaluation of glycoconjugate vaccines, the method could provide more information than the traditional size exclusion chromatography method. Fourteen and twelve reported glycosylation sites for CRM197- and tetanus toxin -based vaccines can be detected, respectively. This article is protected by copyright. All rights reserved.

2.
Eur J Pharmacol ; 876: 173041, 2020 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-32142769

RESUMO

Initiation of necroptosis has been considered as a promising strategy for anticancer therapies, especially for eradicating apoptosis-resistant malignant cells. Jujubisode B is a natural saponins extracted from the seeds of Zizyphi Spinosi Semen, and possesses multiple pharmacological activities, including antianxiety, anti-inflammation, antiplatelet aggregation and induction of apoptosis. This study aims to explore the effect of jujuboside B on acute leukemic cells and the underlying mechanisms. Our results showed that jujuboside B inhibited leukemia cell growth in a dose-dependent manner and attenuated the clonogenic ability of U937 cells, concomitant with activation of RIPK1/RIPK3/MLKL pathway; these phenomena were evidently blocked by necroptosis inhibitor (Nec-1). With the help of Molecular Operating Environment (MOE) program, we identified that RIPK1, RIPK3 and MLKL are potential targets of jujuboside B. To the best of our knowledge, this is the first study to provide evidence that jujuboside B possesses antileukemic activity via a mechanism involving activation of RIPK1/RIPK3/MLKL pathway.

3.
4.
Food Chem ; 312: 126020, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31874410

RESUMO

The aim of this work, which was conducted in 2017 and 2018, was to gain insight into the effects of regulated deficit irrigation (RDI) treatments on the content of soluble sugars, organic acids and endogenous hormones in Cabernet Sauvignon. The RDI treatments slightly decreased the hundred-grain weight and total acid content before vintage but significantly increased the soluble solids content, juice pH and reducing sugar content. The glucose and fructose contents were increased by the RDI treatments, and the ratio of G:F was reduced. Most genes associated with sugar unloading were upregulated by RDI, especially in the RDI1 group. The tartaric acid, malic acid and citric acid contents were decreased by RDI. Under the RDI treatments, the ABA content increased from E-L 33 to 38, and the IAA, GA3, JA-Me and BR contents decreased from E-L 33 to 34. The results of this study ultimately benefit the promotion of RDI measures, and our data might be useful for the improvement of wine grape quality.


Assuntos
Ácidos/análise , Açúcares/análise , Vinho/análise , China , Frutas/química , Compostos Orgânicos/análise , Solubilidade , Vitis/química
5.
Nat Commun ; 10(1): 4599, 2019 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-31601813

RESUMO

Host-guest interactions are of central importance in many biological and chemical processes. However, the investigation of the formation and decomplexation of host-guest systems at the single-molecule level has been a challenging task. Here we show that the single-molecule conductance of organoplatinum(II) metallocycle hosts can be enhanced by an order of magnitude by the incorporation of a C60 guest molecule. Mechanically stretching the metallocycle-C60 junction with a scanning tunneling microscopy break junction technique causes the release of the C60 guest from the metallocycle, and consequently the conductance switches back to the free-host level. Metallocycle hosts with different shapes and cavity sizes show different degrees of flexibility to accommodate the C60 guest in response to mechanical stretching. DFT calculations provide further insights into the electronic structures and charge transport properties of the molecular junctions based on metallocycles and the metallocycle-C60 complexes.


Assuntos
Fulerenos/química , Compostos Organoplatínicos/química , Teoria da Densidade Funcional , Eletrodos , Ouro , Espectroscopia de Ressonância Magnética , Microscopia de Força Atômica , Microscopia de Tunelamento , Espectrofotometria Ultravioleta
6.
Int J Clin Pharmacol Ther ; 57(11): 552-560, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31397275

RESUMO

OBJECTIVE: This study was conducted to evaluate the difference in acid inhibition function among lansoprazole (LPZ), pantoprazole (PPZ), and their respective stereoisomers following single and multiple intravenous doses in healthy Chinese subjects. MATERIALS AND METHODS: The dosage groups were set as follows: 30 mg single and multiple intravenous administrations of LPZ or R-LPZ, 40 mg single and multiple intravenous administrations of PPZ or S-PPZ. Subjects received an intravenous infusion of LPZ, R-LPZ, PPZ, or S-PPZ injection in sterile saline solution (100 mL/h, 60 minutes), respectively. The intragastric pH was sampled every second for 24 hours at baseline and for 24 hours after drug administration. The baseline-adjusted pharmacodynamic (PD) parameters include ΔMean (pH), ΔMedian (pH), ΔTpH≥3 (%), ΔTpH≥4 (%), ΔTpH≥6 (%), and ΔAUECph-tτ1-τ2. The PD parameters were evaluated in different time intervals (0 - 24 hours, 0 - 4 hours and 14 - 24 hours). RESULTS: After a single dose, the ΔTpH≥4 (%) of R-LPZ, LPZ, S-PPZ and PPZ was 56.6 ± 19.6, 53.1 ± 23.3, 35.6 ± 24.9 and 26.8 ± 30.2, respectively. The ΔTpH≥6 (%) was 50.7 ± 26.1, 41.4 ± 26.2, 25.4 ± 24.9 and 22.1 ± 27.6, respectively. The ΔAUECph-τ1-τ was 45,564 ± 16,107, 41,798 ± 16,153, 31,914 ± 17,304 and 20,744 ± 21,500, respectively. Statistically significant differences were found with R-LPZ vs. S-PPZ, R-LPZ vs. PPZ, LPZ vs. S-PPZ and LPZ vs. PPZ. The average TpH≥4 of R-LPZ, LPZ, S-PPZ, and PPZ was (47.2 ± 26.1) minutes, (49.6 ± 19.3) minutes, (56.1 ± 23.7) minutes, and (72.1 ± 27.3) minutes, respectively. Statistically significant differences were found with R-LPZ vs. PPZ (p = 0.009) and LPZ vs. PPZ (p = 0.019). After multiple doses, the ΔTpH≥4 (%) of R-LPZ, LPZ, S-PPZ, and PPZ was 71.7 ± 20.2, 63.5 ± 19.4, 59.5 ± 17.8 and 64.0 ± 22.4, respectively. The ΔTpH≥6 (%) was 64.0 ± 22.2, 52.0 ± 19.2, 49.6 ± 20.4 and 50.9 ± 23.8, respectively. The ΔAUECph-τ1-τ was 326,149 ± 94,839, 288,565 ± 93,279, 296,189 ± 83,412 and 300,960 ± 108,057, respectively. No statistically significant differences were found in baseline-adjusted PD parameters during all time periods after multiple doses. CONCLUSION: After a single dose, the mean gastric pH inhibition value of R-LPZ was the highest, followed by LPZ, then S-PPZ and PPZ. R-LPZ and LPZ provided significantly better pH control compared with PPZ and S-PPZ in healthy subjects. The onset time of R-LPZ was the fastest and R-LPZ can provide better acid inhibition during sleeping time. After multiple doses, the mean values in all PD parameters of R-LPZ were the highest, the values of LPZ, S-PPZ, and PPZ were similar. However, no significant difference was found in acid inhibition among these four drugs after multiple doses.


Assuntos
Antiulcerosos/farmacologia , Determinação da Acidez Gástrica , Lansoprazol/farmacologia , Pantoprazol/farmacologia , Voluntários Saudáveis , Humanos , Concentração de Íons de Hidrogênio , Estereoisomerismo
7.
Naunyn Schmiedebergs Arch Pharmacol ; 392(9): 1043-1048, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31230091

RESUMO

Gasdermin E (GSDME), also called DFNA5, is a member of the gasdermin family. GSDME is involved in the regulation of apoptosis and necrosis. The N-terminal domain of GSDME displays an apoptosis-inducing activity while the C-terminal domain may serve as an apoptosis-inhibiting regulator by shielding the N-terminal domain. Besides its function in the regulation of apoptosis, GSDME was recently reported to be a substrate of caspase-3 and cleavage of GSDME by caspase-3 into necrotic N-terminal fragment leads to the induction of secondary necrosis. GSDME was first identified as a deafness gene because its mutation was associated with a specific form of autosomal dominant progressive sensorineural hearing loss. Furthermore, GSDME has been considered a tumor suppressor implicated in several types of cancer. This mini-review summarized recent reports relevant to the functions of GSDME in the regulation of apoptosis and necrosis as well as its clinical relevance.

8.
Naunyn Schmiedebergs Arch Pharmacol ; 392(9): 1085-1095, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31055628

RESUMO

Receptor-interacting protein kinase 1/3 (RIPK1/3) and mixed lineage kinase domain-like (MLKL)-mediated necroptosis contributes to brain injury after ischemic stroke. Ligustroflavone is an ingredient of common privet with activities of anti-inflammation and complement inhibition. This study aims to explore the effect of ligustroflavone on ischemic brain injury in stroke rat and the underlying mechanisms. A rat model of ischemic stroke was established by middle cerebral artery occlusion (MCAO), which showed ischemic injury (increase in neurological deficit score and infarct volume) and upregulation of necroptosis-associated proteins (RIPK1, RIPK3 and MLKL/p-MLKL). Administration of ligustroflavone (30 mg/kg, i.g.) 15 min before ischemia evidently improved neurological function, reduced infarct volume, and decreased the levels of necroptosis-associated proteins except the RIPK1. Consistently, hypoxia-cultured PC12 cells (O2/N2/CO2, 1:94:5, 8 h) caused cellular injury (LDH release and necroposis) concomitant with up-regulation of necroptosis-associated proteins, and these phenomena were blocked in the presence of ligustroflavone (25 µM) except the elevated RIPK1 levels. Using the Molecular Operating Environment (MOE) program, we identified RIPK1, RIPK3, and MLKL as potential targets of ligustroflavone. Further studies showed that the interaction between RIPK3 and RIPK1 or MLKL was significantly enhanced, which was blocked in the presence of ligustroflavone. Based on these observations, we conclude that ligustroflavone protects rat brain from ischemic injury, and its beneficial effect is related to the prevention of necroptosis through a mechanism involving targeting RIPK1, RIPK3, and/or MLKL.

9.
J Cell Biochem ; 120(10): 16978-16989, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31111562

RESUMO

The effects of ethoxy-erianin phosphate (EBTP) on cell proliferation, mitotic cell arrest, migration, infiltration, and endothelial tubular structures were evaluated in this study. The antiproliferative activity of EBTP and combretastatin A-4P (CA4P) was analyzed on several tumor cells (including MCF-7, HeLa, 2LL, and 2LL-IDO) and on an endothelial cell (human umbilical vein endothelial cells [HUVECs]) as well as a human normal liver cell (L02). The results showed that EBTP possessed antiproliferative activity in the micromole range and was relatively less toxic than CA4P. Treating HUVECs with EBTP caused cell accumulation in the G2/M phase, and wound-healing assays indicated that EBTP inhibited cell migration. Furthermore, EBTP and CA4P destroyed the vasculature in endothelial cells and showed vascular disrupting activity of the chorioallantoic membrane in fertilized chicken eggs. In addition, we found that EBTP suppressed the expression of indoleamine 2,3-dioxygenase (IDO) and significantly inhibited IDO-induced migration and infiltration of 2LL-IDO cells. Administration of EBTP blocked vasculogenic mimicry in 2LL-IDO cells, which was typically observed in tube formation assays of 2LL-IDO cells. Moreover, the results of Lewis lung carcinoma in mice showed a high inhibition rate of EBTP. EBTP is an effective vascular disrupting agent that is superior to CA4P and may prevent and treat malignancy by inhibiting the expression of IDO.

10.
J Cell Physiol ; 234(12): 22703-22718, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31120140

RESUMO

Colon cancer stem cells (CCSCs) stand for a critical subpopulation of colon cancer cells that possess self-renewal and multilineage differentiation potentials and drive tumorigenicity. Due to their impact on treatment tolerance, CCSCs have been a hot research topic in the past few years. We have previously reported that miR-139-5p is a vital tumor repressive noncoding RNA whose level decreases in the clinical colon cancer samples with the increase of tumor malignancy. This research discovered that miR-139-5p targets the Wnt/ß-catenin/TCF7L2 downstream effector E2-2 in CCSCs. E2-2 is a pivot molecule in the negative feedback loop of miR-139-5p/Wnt/ß-catenin/TCF7L2. Its small interfering RNA reverses the stemness maintenance and epithelial-mesenchymal transition of colon cancer CSCs. This study provides a theoretical foundation for the clinical diagnosis and medical treatment of recurrent or metastatic colon cancer with miR-139-5p and its target E2-2.

11.
J Pharm Biomed Anal ; 169: 30-40, 2019 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-30831450

RESUMO

A liquid chromatography tandem mass spectrometry method (LC-MS/MS) was developed to determine simultaneously the bioactive proteins including pertussis toxin (PT) subunits, filamentous hemagglutinin (FHA), pertactin (PRN) and fimbriae (FIM) in diphtheria, tetanus and acellular pertussis combined vaccine (DTaP). The trypsin digestion conditions were investigated in detail using PT reference to achieve satisfactory results in detection of the peptides on LC-MS/MS with a Bio-C18 column. The performance of the described method was evaluated using reference proteins and the results showed a wide linear range (0.15-24 ng µL-1), a high sensitivity (0.038 ng. µL-1 for FHA) and a good precision (RSD of peak area <3.3%). This novel LC-MS/MS method was applied to determine PT subunits, FHA, PRN and FIM in DTaP vaccines, a total of ten batches, obtained from five manufacturers. The results revealed clearly that batch-to-batch consistency of the DTaP vaccines in terms of the protein amounts was stable, while those from manufacturers were varied significantly. On the other hand, the amount of bioactive proteins in component DTaP vaccines was generally higher than those in co-purified DTaP vaccines. The described LC-MS/MS method was compared with Chinese Pharmacopeia method (Lowry method) and it was found that FHA and PRN amounts measured by the two methods were in good agreement. The LC-MS/MS method could provide the amounts of PT subunits. However, the Lowry method could not differentiate the subunits. The LC-MS/MS method was not only more selective and sensitive, but it can be used to determine simultaneously different bioactive proteins in complex matrix-formulated vaccines. The method was extended successfully in other purposes, such as the effect of detoxification on bioactive proteins and characterization of PT references from four organizations worldwide.


Assuntos
Vacinas contra Difteria, Tétano e Coqueluche Acelular/química , Proteínas/química , Cromatografia Líquida/métodos , Humanos , Espectrometria de Massas em Tandem/métodos
12.
Proc Natl Acad Sci U S A ; 116(9): 3407-3412, 2019 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-30737288

RESUMO

Electron transfer reactions can now be followed at the single-molecule level, but the connection between the microscopic and macroscopic data remains to be understood. By monitoring the conductance of a single molecule, we show that the individual electron transfer reaction events are stochastic and manifested as large conductance fluctuations. The fluctuation probability follows first-order kinetics with potential dependent rate constants described by the Butler-Volmer relation. Ensemble averaging of many individual reaction events leads to a deterministic dependence of the conductance on the external electrochemical potential that follows the Nernst equation. This study discloses a systematic transition from stochastic kinetics of individual reaction events to deterministic thermodynamics of ensemble averages and provides insights into electron transfer processes of small systems, consisting of a single molecule or a small number of molecules.

13.
Nat Mater ; 18(4): 357-363, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30742082

RESUMO

Quantum interference can profoundly affect charge transport in single molecules, but experiments can usually measure only the conductance at the Fermi energy. Because, in general, the most pronounced features of the quantum interference are not located at the Fermi energy, it is highly desirable to probe charge transport in a broader energy range. Here, by means of electrochemical gating, we measure the conductance and map the transmission functions of single molecules at and around the Fermi energy, and study signatures associated with constructive and destructive interference. With electrochemical gate control, we tune the quantum interference between the highest occupied molecular orbital and lowest unoccupied molecular orbital, and directly observe anti-resonance, a distinct feature of destructive interference. By tuning the molecule in and out of anti-resonance, we achieve continuous control of the conductance over two orders of magnitude with a subthreshold swing of ~17 mV dec-1, features relevant to high-speed and low-power electronics.

14.
Eur J Pharmacol ; 849: 50-58, 2019 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-30716316

RESUMO

Methyl protodioscin (MPD) is reported to relieve angina pectoris and myocardial ischemia, and mitochondrial E3 ubiquitin ligase 1 (Mul1) plays a key role in maintaining mitochondrial functions. Bioinformatic analysis shows potential interactions between MPD and Mul1. This study aims to explore whether MPD could protect rat brain against ischemia/reperfusion (I/R) injury through regulation of Mul1/ superoxide dismutase 2 (SOD2) pathway. The SD rat brains were subjected to 2 h of ischemia following by 24 h of reperfusion, which showed I/R injury (increase in neurological deficit score and infarct volume), up-regulation of Mul1 and down regulation of SOD2, these phenomena were attenuated by MPD treatment (3 or 10 mg/kg, i.g.). Consistently, in cultured HT22 cells, hypoxia-reoxygenation (H/R) treatment induced cellular injury (apoptosis and LDH release) concomitant with up-regulation of Mul1 and down regulation of SOD2, these phenomena were blocked in the presence of MPD (5 µM). Knockdown of Mul1 could also decrease SOD2 protein levels in HT22 cells accompanied by alleviation of H/R injury (reduction of apoptosis and LDH release). In agreement with the change of SOD2, reactive oxygen species generation was increased in H/R-treated HT22 cells while decreased in the presence of MPD. Based on these observations, we conclude that upregulation of Mul1 in rat brain contributes to cerebral I/R injury via suppression of SOD2 and that MPD protects rat brain from I/R injury through a mechanism involving regulation of Mul1/SOD2 pathway.


Assuntos
Produtos Biológicos/farmacologia , Encéfalo/efeitos dos fármacos , Diosgenina/análogos & derivados , Proteínas Mitocondriais/metabolismo , Traumatismo por Reperfusão/prevenção & controle , Saponinas/farmacologia , Superóxido Dismutase/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Animais , Apoptose/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/patologia , Caspase 3/metabolismo , Hipóxia Celular/efeitos dos fármacos , Linhagem Celular , Citoproteção/efeitos dos fármacos , Diosgenina/farmacologia , Técnicas de Silenciamento de Genes , Proteínas Mitocondriais/deficiência , Proteínas Mitocondriais/genética , Oxigênio/metabolismo , Ratos , Ratos Sprague-Dawley , Traumatismo por Reperfusão/metabolismo , Traumatismo por Reperfusão/patologia , Ubiquitina-Proteína Ligases/deficiência , Ubiquitina-Proteína Ligases/genética
15.
Se Pu ; 37(2): 155-161, 2019 Feb 08.
Artigo em Chinês | MEDLINE | ID: mdl-30693723

RESUMO

Tracheal cytotoxin (TCT) is a toxic glycopeptide, which contribute to the adverse effects of pertussis toxin (PT) and related vaccines. Although pharmacopeias limit the amount of TCT in PT product, there is no recommended TCT determination method in any pharmacopeia. In this study, a liquid chromatography-tandem mass spectrometry method was developed to determine TCT. Chromatographic conditions, including column-type and mobile-phase composition, were optimized. According to the literature reports, both reversed-phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC) can provide a good retention for TCT. A large amount of organic solvent is usually used for protein precipitation, which may affect the RPLC mode, leading to peak distortion, while such effects were not observed in HILIC mode. Thus, HILIC mode was used to analyze TCT in this study. The developed method had a wide linear range (5.76-369 ng/L), good precision (no more than 3.9%), satisfied recoveries in various matrices (96.4%-102.5%). The limit of quantification (LOQ) of the developed method was 1279 times lower than the one required by Chinese Pharmacopeia, wherein the required amount of TCT should be less than 2 pmol per dose. The developed method was used to detect TCT in pertussis vaccine (acellular component), pertussis vaccine (acellular, co-purified), co-purified diphtheria tetanus pertussis vaccine, and component diphtheria tetanus acellular pertussis vaccine. As a result, TCT was not detected in any of the selected samples indicating the safety of these vaccines and PT products.


Assuntos
Citotoxinas/análise , Vacinas contra Difteria, Tétano e Coqueluche Acelular/análise , Cromatografia Líquida , Espectrometria de Massas em Tandem
16.
Anal Chim Acta ; 1049: 105-114, 2019 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-30612641

RESUMO

In this study, a novel two dimensional liquid chromatography - mass spectrometry (2D-LC-MS) method with use of a weak anion exchange column between the 1st DLC RP column and the 2nd DLC RP column (RP1-WAX-RP2) was developed and applied to identify drug impurities from MS incompatible mobile phases containing sodium 1-octanesulfonate and non-volatile buffer. The 1st DLC conditions follow exactly the original standard HPLC method recorded in Chinese Pharmacopeia (ChP), European Pharmacopeia (EP) or US Pharmacopeia (USP). An impurity fraction was collected with a built-in sample loop (100 µL) and transferred to the WAX column where 1-octanesulfonate and phosphate were trapped and removed. While, the impurity and other cations were eluted to the 2nd D column (RP2) for separation and identification by connected IT-TOF MS. Methods were programmed and applied to identify impurities in two generic drugs, sulpiride (hydrophilic drug with logP 0.57) and dobutamine (hydrophobic drug with logP 3.6). The results indicate that the methods based on RP1-WAX-RP2 column configuration offer a feasible solution for direct impurity identification in generic drug product or API without needs of off-line desalting from the MS incompatible mobile phases containing ion-pairing reagent and non-volatile buffer.


Assuntos
Cromatografia por Troca Iônica/métodos , Dobutamina/análise , Contaminação de Medicamentos , Espectrometria de Massas por Ionização por Electrospray/métodos , Sulpirida/análise , Cromatografia Líquida de Alta Pressão , Cromatografia de Fase Reversa/métodos
17.
Chemosphere ; 216: 324-330, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30384301

RESUMO

The selection of favorable environmental conditions for gravity-driven membrane (GDM) systems is crucial to their widespread application. In this study, GDM systems operated under different light intensities (illuminance levels of 0, 200, and 3000 Lux) and water temperatures (10, 20, and 30 °C) were investigated for their performance and fouling layer characteristics. The results showed that indoor light (200 Lux) had limited effects on the performance of the GDM system. However, full daylight (3000 Lux) led to algal growth; these algae increased fouling resistance and deteriorated permeate water by releasing algogenic organic matter, although they could also enhance the heterogeneity of the biofouling layer by increasing the microbial activity. Water temperature rarely influenced the total organic matter removal. The fouling layers had different thicknesses and heterogeneity, but the same level of EPS; therefore, the hydraulic resistances of these fouling layer were almost the same at different water temperatures. These findings suggest that GDM system could be operated at low water temperature and indoor light conditions, and that strong light should be avoided during the operation of GDM systems.


Assuntos
Cianobactérias/química , Luz , Água/química , Gravitação , Membranas Artificiais , Temperatura
18.
J Am Chem Soc ; 140(51): 18074-18081, 2018 12 26.
Artigo em Inglês | MEDLINE | ID: mdl-30500187

RESUMO

Providing a mechanically stable and electronically efficient coupling between a molecule and an electrode is critical to the study of charge transfer and conductance of the molecule. A common method is to link the molecule to Au electrodes via a linker (e.g., thiol terminal of the molecule). Here we study the mechanical stability and electronic coupling of a S-Au bond in single-molecule junctions over a broad range of electrode potentials. Our results show that the mechanical and electromechanical properties of molecule-electrode contact undergo a systematic change with the potential involving Au oxidation at positive potentials and S protonation at negative potentials. The study establishes the potential range for a stable S-Au bond and determines the potential dependence of the mechanical and electromechanical properties of the molecule-electrode contact, which is crucial to the interpretation of potential-dependent charge transfer in electrochemistry and electrochemical gating of charge transport in molecular electronics.

19.
J Cell Biochem ; 2018 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-30378153

RESUMO

Hyperthermia enhances the anticancer effects of thymidylate synthase (TYMS) inhibitors (raltitrexed, RTX) and improves the precise biochemical mechanisms partially through enhancement of intracellular drug absorption. Recent research focuses on the potential anticancer drug target Heat Shock Protein 90 (HSP90), which could increase the sensitivity of cancer cells to TYMS inhibitors; however, with different HSP90 inhibitors, several research studies finally showed a poor efficacy in preclinical or clinical research. Here, we showed that 17-allylamino-17-demethoxygeldanamycin (17-AAG, HSP90 inhibitor) affects the efficacy of chemotherapy through antioxidant activation-induced resistance. In this study, we found that RTX, alone or in combination with hyperthermia, triggers reactive oxygen species (ROS) exposure and thus induces cell death. Also, the addition of hyperthermia showed more ROS exposure and function. The pharmacologic inhibition of HSP90 reversed the effects of chemotherapeutical treatments, while the overexpression of HSP90 showed no relation with these effects, which demonstrated that dysregulation of HSP90 might have a significant impact on chemotherapeutic treatments. The addition of 17-AAG increased the activation of antioxidant with increased antioxidant enzymes, thus affecting the RTX efficacy.

20.
Talanta ; 190: 9-14, 2018 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-30172547

RESUMO

A column-switching system, composed of supercritical fluid chromatography (SFC) and reverse phase liquid chromatography/mass spectrometry (RPLC/MS) was developed for the analysis of vitamin D in oily and fatty matrices. The SFC with the similar retention behavior as normal-phase liquid chromatography (NPLC), was applied for an on-line clean-up of oily and fatty samples, then followed by separation and detection using a reverse-phase LC-MS/MS. Three SFC columns packed with materials of different functional groups (Silica, NH2, Diol) were compared and the column with diol groups, on which the retention time of vitamin D was the longest, was finally selected for purification of the samples. 100% methanol was chosen to carry vitamin D from the clean-up column to the pre-treatment column. It was also used as the mobile phase for the separation of vitamin D on a reverse phase C18 column. Vitamin D2 and D3 were baseline separated by using this system. The linearity was calculated with a value of coefficient of determination (r2) ≥ 0.998. The linear range is from 20 ng/mL to 200 ng/mL. Two kinds of liquid vitamin D3 supplements (Baby Ddrops and Vitamin AD drops) were directly analyzed using this system without any fussy preparation procedure. The limit of detection (LOD) for vitamin D3 in the two oily samples was estimated to be 10 ng/mL. The relative standard deviations (RSD) of intra- and inter-day precision, repeatability were 1.47%, 2.43% and 1.59% for Baby Ddrops and 5.76%, 8.24% and 5.86% for Vitamin AD drops. The recoveries vary between 84.3% and 102.8% with 7.1% RSD for Baby Ddrops and 90.8-109.6% with 5.83% RSD for Vitamin AD drops, respectively. These results suggest that the method based on the SFC-RPLC/MS column-switching system is simple and suitable for analysis of vitamin D in oily and fatty samples.


Assuntos
Cromatografia com Fluido Supercrítico/métodos , Óleos/química , Vitamina D/análise , Calibragem , Colecalciferol/análise , Colecalciferol/isolamento & purificação , Suplementos Nutricionais/análise , Limite de Detecção , Vitamina D/isolamento & purificação
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