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1.
J Org Chem ; 89(14): 9750-9754, 2024 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-38940722

RESUMEN

Herein, a photocatalytic umpolung strategy for reductive carboxylation of imines for the synthesis of α-amino acids was disclosed. Carbon dioxide radical anion (CO2•-) generated from formate is the key single electron reductant in the reactions. An unprecedentedly broad substrate scope of imines with excellent reaction yields was obtained with carbon dioxide (CO2) and formate salt as carbon sources.

2.
BMC Vet Res ; 20(1): 191, 2024 May 11.
Artículo en Inglés | MEDLINE | ID: mdl-38734611

RESUMEN

BACKGROUND: Many proteins of African swine fever virus (ASFV, such as p72, p54, p30, CD2v, K205R) have been successfully expressed and characterized. However, there are few reports on the DP96R protein of ASFV, which is the virulence protein of ASFV and plays an important role in the process of host infection and invasion of ASFV. RESULTS: Firstly, the prokaryotic expression vector of DP96R gene was constructed, the prokaryotic system was used to induce the expression of DP96R protein, and monoclonal antibody was prepared by immunizing mice. Four monoclonal cells of DP96R protein were obtained by three ELISA screening and two sub-cloning; the titer of ascites antibody was up to 1:500,000, and the monoclonal antibody could specifically recognize DP96R protein. Finally, the subtypes of the four strains of monoclonal antibodies were identified and the minimum epitopes recognized by them were determined. CONCLUSION: Monoclonal antibody against ASFV DP96R protein was successfully prepared and identified, which lays a foundation for further exploration of the structure and function of DP96R protein and ASFV diagnostic technology.


Asunto(s)
Virus de la Fiebre Porcina Africana , Anticuerpos Monoclonales , Epítopos , Ratones Endogámicos BALB C , Proteínas Virales , Animales , Femenino , Ratones , Fiebre Porcina Africana/inmunología , Fiebre Porcina Africana/virología , Virus de la Fiebre Porcina Africana/inmunología , Anticuerpos Monoclonales/inmunología , Anticuerpos Antivirales/inmunología , Epítopos/inmunología , Porcinos , Proteínas Virales/inmunología
3.
J Craniofac Surg ; 35(1): 168-171, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-37815293

RESUMEN

OBJECTIVE: The aim of this study was to conclude the safety and effectiveness of hybrid surgery for revascularization of chronic occlusion of internal carotid artery (COICA). METHODS: A total of 56 COCIA patients underwent hybrid surgery (carotid endarterectomy+carotid artery stenting) from September 2017 to September 2021 in our department. The clinical material and radiology data (preoperation and postoperation) were retrospectively analyzed to conclude the safety and effectiveness of hybrid surgery for revascularization of COICA. RESULTS: All 56 patients underwent hybrid surgery got revascularization successfully (with a successful rate of 100%) and improved intracranial blood flow. The computed tomography perfusion results indicate that the postoperative cerebral blood flow perfusion of the patient is significantly improved compared with before surgery. In 1 patient, postoperative brain magnetic resonance imaging within 24 hours showed spotted fresh infarction with head magnetic resonance imaging, without any clinical symptoms; 3 patients developing symptoms of ipsilateral neural-functional defect (hypoglossal nerve, superior laryngeal nerve, and mandibular branch of facial nerve, respectively), 2 weeks later the symptoms were disappeared. Imaging study at 3 and 6 months during the follow-up showed no abnormalities. CONCLUSION: Hybrid surgery is safe and effective for revascularization of COICA.


Asunto(s)
Estenosis Carotídea , Revascularización Cerebral , Endarterectomía Carotidea , Humanos , Arteria Carótida Interna/diagnóstico por imagen , Arteria Carótida Interna/cirugía , Estenosis Carotídea/diagnóstico por imagen , Estenosis Carotídea/cirugía , Endarterectomía Carotidea/métodos , Estudios Retrospectivos , Stents , Resultado del Tratamiento
4.
Nano Lett ; 23(21): 9851-9857, 2023 Nov 08.
Artículo en Inglés | MEDLINE | ID: mdl-37871176

RESUMEN

Constructing two-dimensional (2D) artificial superlattices based on single-atom and few-atom nanoclusters is of great interest for exploring exotic physics. Here we report the realization of two types of artificial germanium (Ge) superlattice self-confined by a 37×37 R25.3° superstructure of bismuth (Bi) induced electronic kagome lattice potential valleys. Scanning tunneling microscopy measurements demonstrate that Ge atoms prefer to be confined in the center of the Bi electronic kagome lattice, forming a single-atom superlattice at 120 K. In contrast, room temperature grown Ge atoms and clusters are confined in the sharing triangle corner and the center, respectively, of the kagome lattice potential valleys, forming an artificial honeycomb superlattice. First-principle calculations and Mulliken population analysis corroborate that our reported atomically thin Bi superstructure on Au(111) has a kagome surface potential valley with the center of the inner Bi hexagon and the space between the outer Bi hexagons being energetically favorable for trapping Ge atoms.

5.
Angew Chem Int Ed Engl ; 63(13): e202319728, 2024 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-38285535

RESUMEN

Organic molecules bearing chiral sulfur stereocenters exert a great impact on asymmetric catalysis and synthesis, chiral drugs, and chiral materials. Compared with acyclic ones, the catalytic asymmetric synthesis of thio-heterocycles has largely lagged behind due to the lack of efficient synthetic strategies. Here we establish the first modular platform to access chiral thio-oxazolidinones via Pd-catalyzed asymmetric [3+2] annulations of vinylethylene carbonates with sulfinylanilines. This protocol is featured by readily available starting materials, and high enantio- and diastereoselectivity. In particular, an unusual effect of a non-chiral supporting ligand on the diastereoselectivity was observed. Possible reaction mechanisms and stereocontrol models were proposed.

6.
Thorax ; 78(2): 211-213, 2023 02.
Artículo en Inglés | MEDLINE | ID: mdl-36261274

RESUMEN

Rosai-Dorfman disease (RDD) is a non-malignant condition mainly manifesting as a proliferation of histiocytes in lymph nodes. Endotracheal RDD (ERDD) with an acute onset presentation is extremely rare. There are few case reports of ERDD mainly concerning its pathology, diagnostics and bronchoscopic treatment, without providing sufficient clinical information from a comprehensive perspective. As a novel and challenging technique, tracheal resection and reconstruction (TRR) with spontaneous-ventilation video-assisted thoracoscopic surgery (SV-VATS) has been reported as feasible and safe in highly selected patients, but few centres have shared their experience with this approach. This case-based discussion includes not only practical issues in the management of a life-threatening ERDD patient, but also specialists' views on the management of acute obstructive airway, and the surgeons' reflection on TRR with SV-VATS.


Asunto(s)
Obstrucción de las Vías Aéreas , Histiocitosis Sinusal , Humanos , Histiocitosis Sinusal/diagnóstico , Histiocitosis Sinusal/cirugía , Histiocitosis Sinusal/patología , Tráquea/cirugía , Tráquea/patología , Histiocitos/patología
7.
Org Biomol Chem ; 21(21): 4429-4433, 2023 May 31.
Artículo en Inglés | MEDLINE | ID: mdl-37191166

RESUMEN

The rhodium-catalyzed ring-opening coupling of cyclic vinyl ethers, including 2,3-dihydrofuran and benzofuran, with organometallic reagents to give homoallylic alcohols and stilbenoids was reported. The suitable organometallic reagent for 2,3-dihydrofuran and benzofuran was found to be substrate-dependent, and a plausible mechanism involving different active organorhodium intermediates was proposed for these coupling reactions.

8.
Hereditas ; 160(1): 29, 2023 Jun 22.
Artículo en Inglés | MEDLINE | ID: mdl-37349788

RESUMEN

BACKGROUND: Glioma stem cells (GSCs) are responsible for glioma recurrence and drug resistance, yet the mechanisms underlying their maintenance remains unclear. This study aimed to identify enhancer-controlled genes involved in GSCs maintenance and elucidate the mechanisms underlying their regulation. METHODS: We analyzed RNA-seq data and H3K27ac ChIP-seq data from GSE119776 to identify differentially expressed genes and enhancers, respectively. Gene Ontology analysis was performed for functional enrichment. Transcription factors were predicted using the Toolkit for Cistrome Data Browser. Prognostic analysis and gene expression correlation was conducted using the Chinese Glioma Genome Atlas (CGGA) data. Two GSC cell lines, GSC-A172 and GSC-U138MG, were isolated from A172 and U138MG cell lines. qRT-PCR was used to detect gene transcription levels. ChIP-qPCR was used to detect H3K27ac of enhancers, and binding of E2F4 to target gene enhancers. Western blot was used to analyze protein levels of p-ATR and γH2AX. Sphere formation, limiting dilution and cell growth assays were used to analyze GSCs growth and self-renewal. RESULTS: We found that upregulated genes in GSCs were associated with ataxia-telangiectasia-mutated-and-Rad3-related kinase (ATR) pathway activation, and that seven enhancer-controlled genes related to ATR pathway activation (LIN9, MCM8, CEP72, POLA1, DBF4, NDE1, and CDKN2C) were identified. Expression of these genes corresponded to poor prognosis in glioma patients. E2F4 was identified as a transcription factor that regulates enhancer-controlled genes related to the ATR pathway activation, with MCM8 having the highest hazard ratio among genes positively correlated with E2F4 expression. E2F4 bound to MCM8 enhancers to promote its transcription. Overexpression of MCM8 partially restored the inhibition of GSCs self-renewal, cell growth, and the ATR pathway activation caused by E2F4 knockdown. CONCLUSION: Our study demonstrated that E2F4-mediated enhancer activation of MCM8 promotes the ATR pathway activation and GSCs characteristics. These findings offer promising targets for the development of new therapies for gliomas.


Asunto(s)
Glioma , Humanos , Glioma/genética , Glioma/metabolismo , Factores de Transcripción/metabolismo , Proliferación Celular/genética , Células Madre Neoplásicas/metabolismo , Proteínas de Mantenimiento de Minicromosoma/metabolismo , Factor de Transcripción E2F4/metabolismo , Proteínas Asociadas a Microtúbulos , Proteínas de la Ataxia Telangiectasia Mutada/metabolismo
9.
BMC Palliat Care ; 22(1): 197, 2023 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-38087276

RESUMEN

BACKGROUND: Hospice and Palliative Care (HPC) is in high demand in China; however, the country is facing the shortage of qualified HPC nurses. A well-suited competence framework is needed to promote HPC human resource development. Nevertheless, existing unstandardized single-structured frameworks may not be sufficient to meet this need. This study aimed at constructing a comprehensive multi-structured HPC competence framework for nurses. METHODS: This study employed a mixed-method approach, including a systematic review and qualitative interview for HPC competence profile extraction, a two-round Delphi survey to determine the competences for the framework, and a cross-sectional study for framework structure exploration. The competence profiles were extracted from publications from academic databases and interviews recruiting nurses working in the HPC field. The research team synthesized profiles and transferred them to competences utilizing existing competence dictionaries. These synthesized competences were then subjected to Delphi expert panels to determine the framework elements. The study analyzed theoretical structure of the framework through exploratory factor analysis (EFA) based on a cross-sectional study receiving 491 valid questionnaires. RESULTS: The systematic review involved 30 publications from 10 countries between 1995 and 2021, while 13 nurses from three hospitals were interviewed. In total, 87 and 48 competence profiles were respectively extracted from systematic review and interview and later synthesized into 32 competences. After the Delphi survey, 25 competences were incorporated into the HPC competence framework for nurses. The EFA found a two-factor structure, with factor 1 comprising 18 competences namely Basic Competences; factor 2 concluding 7 competences namely Developmental Competences. CONCLUSIONS: The two-factor HPC competence framework provided valuable insights into the need and directions of Chinese HPC nurses' development.


Asunto(s)
Cuidados Paliativos al Final de la Vida , Enfermería de Cuidados Paliativos al Final de la Vida , Hospitales para Enfermos Terminales , Enfermeras y Enfermeros , Humanos , Competencia Clínica , Estudios Transversales , Cuidados Paliativos , Encuestas y Cuestionarios , Revisiones Sistemáticas como Asunto
10.
Molecules ; 28(17)2023 Aug 24.
Artículo en Inglés | MEDLINE | ID: mdl-37687063

RESUMEN

As a biodegradable and renewable material, polylactic acid is considered a major environmentally friendly alternative to petrochemical plastics. Microbial fermentation is the traditional method for lactic acid production, but it is still too expensive to compete with the petrochemical industry. Agro-industrial wastes are generated from the food and agricultural industries and agricultural practices. The utilization of agro-industrial wastes is an important way to reduce costs, save energy and achieve sustainable development. The present study aimed to develop a method for the valorization of Zizania latifolia waste and cane molasses as carbon sources for L-lactic acid fermentation using Rhizopus oryzae LA-UN-1. The results showed that xylose derived from the acid hydrolysis of Z. latifolia waste was beneficial for cell growth, while glucose from the acid hydrolysis of Z. latifolia waste and mixed sugars (glucose and fructose) from the acid hydrolysis of cane molasses were suitable for the accumulation of lactic acid. Thus, a three-stage carbon source utilization strategy was developed, which markedly improved lactic acid production and productivity, respectively reaching 129.47 g/L and 1.51 g/L·h after 86 h of fermentation. This work demonstrates that inexpensive Z. latifolia waste and cane molasses can be suitable carbon sources for lactic acid production, offering an efficient utilization strategy for agro-industrial wastes.


Asunto(s)
Melaza , Rhizopus oryzae , Bastones , Residuos Industriales , Ácido Láctico , Carbono , Glucosa
11.
Fa Yi Xue Za Zhi ; 39(4): 406-416, 2023 Aug 25.
Artículo en Inglés, Zh | MEDLINE | ID: mdl-37859481

RESUMEN

In recent years, the types and quantities of fentanyl analogs have increased rapidly. It has become a hotspot in the illicit drug control field of how to quickly identify novel fentanyl analogs and to shorten the blank regulatory period. At present, the identification methods of fentanyl analogs that have been developed mostly rely on reference materials to target fentanyl analogs or their metabolites with known chemical structures, but these methods face challenges when analyzing new compounds with unknown structures. In recent years, emerging machine learning technology can quickly and automatically extract valuable features from massive data, which provides inspiration for the non-targeted screening of fentanyl analogs. For example, the wide application of instruments like Raman spectroscopy, nuclear magnetic resonance spectroscopy, high resolution mass spectrometry, and other instruments can maximize the mining of the characteristic data related to fentanyl analogs in samples. Combining this data with an appropriate machine learning model, researchers may create a variety of high-performance non-targeted fentanyl identification methods. This paper reviews the recent research on the application of machine learning assisted non-targeted screening strategy for the identification of fentanyl analogs, and looks forward to the future development trend in this field.


Asunto(s)
Fentanilo , Drogas Ilícitas , Detección de Abuso de Sustancias/métodos , Espectrometría de Masas/métodos , Drogas Ilícitas/análisis
12.
Fa Yi Xue Za Zhi ; 39(2): 144-150, 2023 Apr 25.
Artículo en Inglés, Zh | MEDLINE | ID: mdl-37277377

RESUMEN

OBJECTIVES: To identify 1-(4-fluorophenyl)-2-(1-pyrrolidinyl) pentan-1-one (4-F-α-PVP) analog 1-(4-fluoro-3-methyl phenyl)-2-(1-pyrrolidinyl) pentan-1-one (4-F-3-Methyl-α-PVP) hydrochloride without reference substance. METHODS: The direct-injection electron ionization-mass spectrometry (EI-MS), GC-MS, electrospray ionization-high resolution mass spectrometry (ESI-HRMS), ultra-high performance liquid chromatography-high resolution tandem mass spectrometry (UPLC-HRMS/MS), nuclear magnetic resonance (NMR), ion chromatography and Fourier transform infrared spectroscopy (FTIR) were integrated utilized to achieve the structural analysis and characterization of the unknown compound in the sample, and the cleavage mechanism of the fragment ions was deduced by EI-MS and UPLC-HRMS/MS. RESULTS: By analyzing the direct-injection EI-MS, GC-MS, ESI-HRMS and UPLC-HRMS/MS of the compound in the samples, it was concluded that the unknown compound was a structural analog of 4-F-α-PVP, possibly with one more methyl group in the benzene ring. According to the analysis results of 1H-NMR and 13C-NMR, it was further proved that the methyl group is located at the 3-position of the benzene ring. Since the actual number of hydrogen in 1H-NMR analysis was one more than 4-F-3-Methyl-α-PVP neutral molecule, it was inferred that the compound existed in the form of salt. Ion chromatography analysis results showed that the compound contained chlorine anion (content 11.14%-11.16%), with the structural analysis of main functional group information by FTIR, the unknown compound was finally determined to be 4-F-3-Methyl-α-PVP hydrochloride. CONCLUSIONS: A comprehensive method using EI-MS, GC-MS, ESI-HRMS, UPLC-HRMS/MS, NMR, ion chromatography and FTIR to identify 4-F-3-Methyl-α-PVP hydrochloride in samples is established, which will be helpful for the forensic science laboratory to identify this compound or other analog compounds.


Asunto(s)
Benceno , Espectrometría de Masa por Ionización de Electrospray , Cromatografía de Gases y Espectrometría de Masas/métodos , Cromatografía Líquida de Alta Presión/métodos
13.
Anal Chem ; 94(16): 6216-6224, 2022 04 26.
Artículo en Inglés | MEDLINE | ID: mdl-35420783

RESUMEN

Specific locations of carbon-carbon double bonds (C═C) in lipids often play an essential role in biological processes, and there has been a booming development in C═C composition analysis by mass spectrometry. However, a universal derivatization and fragmentation pattern for the annotation of C═C positions in lipids is still challenging and attractive. To expand this field in lipidomics, a flexible and convenient N-tosylaziridination method was developed, with high derivatization efficiency, sensitivity, and specificity. The derivatization was very fast (15 s), and C═C numbers as well as locations could be pinpointed specifically in tandem mass spectra. By qualitative and quantitative studies of paratumor and tumor thyroid tissues of human beings, the total content of unsaturated fatty acids was suggested to be increased in tumor tissues, and good correlations in and between lysophosphatidylcholines and phosphatidylcholines were revealed by Spearman analysis. Further studies of C═C isomers showed that n-6/n-3 ratios were closely associated with human thyroid tumorigenesis, and high ratios of n-6/n-3 isomers seemed to suffer a high risk of carcinogenesis. Other isomers were not very representative; however, C═C in n-9/n-7 could also be significant for oncology research. Generally, it is supposed that both total amounts and C═C isomer ratios were related to cancer, and N-tosylaziridine derivatization could provide an alternative strategy for the C═C isomer study of disease models.


Asunto(s)
Fosfatidilcolinas , Glándula Tiroides , Carbono , Cloraminas , Ácidos Grasos Insaturados/análisis , Humanos , Espectrometría de Masas en Tándem/métodos , Compuestos de Tosilo
14.
Anal Chem ; 94(50): 17606-17615, 2022 12 20.
Artículo en Inglés | MEDLINE | ID: mdl-36473140

RESUMEN

The amine submetabolome, including amino acids (AAs) and biogenic amines (BAs), is a class of small molecular compounds exhibiting important physiological activities. Here, a new pyrylium salt named 6,7-dimethoxy-3-methyl isochromenylium tetrafluoroborate ([d0]-DMMIC) with stable isotope-labeled reagents ([d3]-/[d6]-DMMIC) was designed and synthesized for amino compounds. [d0]-/[d3]-/[d6]-DMMIC-derivatized had a charged tag and formed a set of molecular ions with an increase of 3.02 m/z and the characteristic fragment ions of m/z 204.1:207.1:210.1. When DMMIC coupled with liquid chromatography-mass spectrometry (LC-MS), a systematic methodology evaluation for quantitation proved to have good linearity (R2 between 0.9904 and 0.9998), precision (interday: 2.2-21.9%; intraday: 1.0-19.7%), and accuracy (recovery: 71.8-108.8%) through the test AAs. Finally, the methods based on DMMIC and LC-MS demonstrated the advantaged application by the nontargeted screening of BAs in a common medicinal herb Senecio scandens and an analysis of metabolic differences among the amine submetabolomes between the carcinoma and paracarcinoma tissues of esophageal squamous cell carcinoma (ESCC). A total of 20 BA candidates were discovered in S. scandens as well as the finding of 13 amine metabolites might be the highest-potential differential metabolites in ESCC. The results showed the ability of DMMIC coupled with LC-MS to analyze the amine submetabolome in herbs and clinical tissues.


Asunto(s)
Neoplasias Esofágicas , Carcinoma de Células Escamosas de Esófago , Humanos , Cromatografía Liquida/métodos , Espectrometría de Masas en Tándem/métodos , Aminoácidos/química , Aminas Biogénicas , Cloruro de Sodio , Isótopos de Carbono/química
15.
Phys Rev Lett ; 128(12): 126401, 2022 Mar 25.
Artículo en Inglés | MEDLINE | ID: mdl-35394312

RESUMEN

Recent transport studies have demonstrated the great potential of twisted monolayer-bilayer graphene (TMBG) as a new platform to host moiré flat bands with a higher tunability than twisted bilayer graphene (TBG). However, a direct visualization of the flat bands in TMBG and its comparison with the ones in TBG remain unexplored. Here, via fabricating on a single sample with exactly the same twist angle of ∼1.13°, we present a direct comparative study between TMBG and TBG using scanning tunneling microscopy and spectroscopy. We observe a sharp density of states peak near the Fermi energy in tunneling spectroscopy, confirming unambiguously the existence of flat electronic bands in TMBG. The bandwidth of this flat-band peak is found to be slightly narrower than that of the TBG, validating previous theoretical predictions. Remarkably, by measuring spatially resolved spectroscopy, combined with continuum model calculation, we show that the flat-band states in TMBG exhibit a unique layer-resolved localization-delocalization coexisting feature, which offers an unprecedented possibility to utilize their cooperation on exploring novel correlation phenomena. Our work provides important microscopic insight of flat-band states for better understanding the emergent physics in graphene moiré systems.

16.
Org Biomol Chem ; 20(6): 1196-1199, 2022 02 09.
Artículo en Inglés | MEDLINE | ID: mdl-35072683

RESUMEN

The visible-light-mediated tandem phosphorylation/cyclization of N-arylacrylamides with H-phosphine oxides has been developed for the synthesis of phosphorylated oxindoles. This efficient and facile process was useful for the construction of a C-P bond and triggered the formation of a C-C bond with good compatibility with functional groups undermild reaction conditions.

17.
Anal Chem ; 93(10): 4576-4583, 2021 03 16.
Artículo en Inglés | MEDLINE | ID: mdl-33656332

RESUMEN

In vitro noncontact cell-based coculture models are frequently employed to study cell-to-cell communication. However, these models cannot accurately represent the complexity of in vivo signaling. d-Lactate is an unusual metabolite produced and released by cancer cells. The characterization of d-lactate is challenging as it shares the same mass but has much lower amounts compared with l-lactate. Herein, d-α-hydroxy acids were specifically recognized and dehydrogenated by d-α-hydroxy acid dehydrogenase. The dehydrogenation products were rapidly quaternized for enhancement of mass signals. An on-probe enzymatic dehydrogenation-derivatization method was proposed for chiral analysis of α-hydroxy acids at the single-cell level. It is a promising amplification methodology and affords over 3 orders of magnitude signal enhancement. Furthermore, direct contact coculture models were used to precisely mimic the tumor microenvironment and explore the communication between cancer and normal cells. Single-cell mass spectrometry (SCMS) was further applied to easily sample cell extracts and study the differences of the aspects of small molecule metabolism in cocultured cells. On the basis of direct contact coculture SCMS, several differential small molecule metabolites and differences of oxidative stress between cocultured and monocultured normal cells were successfully detected. Additionally, d-lactate was discovered as a valuable differential metabolite with application of the two developed methods. It may account for the cancer-associated metabolic behavior of normal cells. These changes could be relieved after d-lactate metabolism-related drug treatment. This discovery may promote the investigation of d-lactate metabolism, which may provide a novel direction for cancer therapy.


Asunto(s)
Comunicación Celular , Ácido Láctico , Técnicas de Cocultivo , Espectrometría de Masas , Transducción de Señal
18.
Anal Chem ; 93(36): 12480-12486, 2021 09 14.
Artículo en Inglés | MEDLINE | ID: mdl-34474566

RESUMEN

Fingerprinting spectra of polymer materials containing information of monomers' molecular weight and detailed structure, constituents, and sequences were obtained by a direct analytical process using arc plasma-based dissociation (APD)-mass spectrometry. The thermal arc plasma generated using a simple arc discharge device induces the dissociation of the polymeric backbone, producing mass spectra with strong regularity within seconds. The molecular weight of the repeating unit was revealed by equal intervals between peak series and protonated monomer ions in the mass spectra. Meanwhile, lots of secondary fragment ions were produced to provide abundant structural information. For polyethers, it is even possible to decipher (read) the "sequence" directly from their spectra. Polymers composed of isomers or only differing in their initiator moieties were easily distinguished with their characteristic APD mass spectra. The spectra were highly reproducible according to the results of similarity calculation. Unlike pyrolysis mass spectrometry, in the APD device, polymers in liquid, solid, powder, and crude samples can be analyzed directly without any pretreatment, and the regular spectra are easier to interpret. Compared with other direct analytical methods, more structural informative spectra can be acquired owing to the high energy, high temperature, and unique chemical reactivity of arc plasma. Thus, this technique is promising to be a valuable tool in rapid elucidation of polymer materials.


Asunto(s)
Polímeros , Iones , Isomerismo , Espectrometría de Masas , Peso Molecular
19.
Fish Shellfish Immunol ; 109: 20-33, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-32991991

RESUMEN

This study was performed to determine effects of dietary isoleucine (Ile) on growth performance, and intestinal immunological and physical barrier function of hybrid catfish Pelteobagrus vachelli × Leiocassis longirostris. Six hundred and thirty fish (33.11 ± 0.09 g) were randomly divided into seven experimental groups with three replicates each, and respectively fed seven diets with 5.0, 7.5, 10.0, 12.5, 15.0, 17.5, and 20.0 g Ile kg-1 diets for 8 weeks. The results showed improvement of growth performance, feed intake, feed utilization, relative gut length (RGL), and intestinal fold height and width by dietary Ile (P < 0.05). Meanwhile, dietary Ile (12.5 g kg-1 diet) improved the activities of lysozyme (LZM), acid phosphatase, alkaline phosphatase and the contents of complement 3 (C3), C4, and immunoglobulin M (IgM) (P < 0.05). The c-type-lectin, c-LZM, g-LZM, and hepcidin mRNA expressions in the intestine were up-regulated in fish fed diets with 10.0-20.0 g Ile kg-1 diet (P < 0.05). Dietary Ile (10.0-12.5 g Ile kg-1 diet) increased intestinal ß-defensin mRNA expression partially in association with Sirt1/ERK/90RSK signaling pathway. Dietary Ile (12.5-15.0 g Ile kg-1 diet) decreased oxidative damage and improved antioxidant ability by increasing activities and expressions of superoxide dismutase, glutathione peroxidase, and glutathione reductase, glutathione-S-transferase (P < 0.05). The occludin, ZO-1, ZO-2, claudin3, and claudin 7 mRNA expressions in the intestine were up-regulated in fish fed diets with 10.0 and 12.5 g Ile kg-1 diet (P < 0.05), whereas the myosin light chain kinase gene expression was decreased in fish fed diets with 7.5-17.5 g Ile kg-1 diet. Dietary Ile (10-12.5 g Ile kg-1 diet) decreased apoptotic responses by reducing the expression of caspase3 and caspase 9 via the AKT/TOR signaling pathway. Based on the quadratic regression analysis of PWG, the dietary Ile requirement of hybrid catfish was estimated to be 12.43 g Ile kg-1 diet, corresponding to 32.05 g Ile kg-1 dietary protein. Collectively, dietary Ile improved growth performance and immunological and physical barrier function of intestine in hybrid catfish.


Asunto(s)
Aminoácidos Esenciales/metabolismo , Bagres/inmunología , Intestinos/inmunología , Isoleucina/metabolismo , Aminoácidos Esenciales/administración & dosificación , Alimentación Animal/análisis , Animales , Apoptosis/inmunología , Bagres/crecimiento & desarrollo , Dieta/veterinaria , Suplementos Dietéticos/análisis , Relación Dosis-Respuesta a Droga , Hibridación Genética , Isoleucina/administración & dosificación , Distribución Aleatoria , Transducción de Señal/inmunología , beta-Defensinas/inmunología , beta-Defensinas/metabolismo
20.
Mikrochim Acta ; 188(8): 246, 2021 07 07.
Artículo en Inglés | MEDLINE | ID: mdl-34235593

RESUMEN

Magnetic covalent organic framework nanocomposite denoted as Fe3O4@TAPB-Tp with core-shell structure was fabricated via a simple template-mediated precipitation polymerization method at mild conditions. The polyimine network shell was created through the polymerization of 1,3,5-tris(4-aminophenyl)-benzene (TAPB) and 1,3,5-triformyl-phloroglucinol (Tp) in tetrahydrofuran (THF) by the Schiff-base reaction. Featuring with large specific surface area (163.19 m2 g-1), good solution dispersibility, and high stability, the obtained Fe3O4@TAPB-Tp exhibited high adsorption capacities and fast adsorption for zearalenone and its derivatives (ZEAs). The adsorption isotherms showed multilayer adsorption dominated at low concentration and monolayer adsorption at high concentration between the interface of ZEAs and Fe3O4@TAPB-Tp. With the Fe3O4@TAPB-Tp as sorbent, a magnetic solid-phase extraction-ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was established for simultaneous adsorption and detection of five ZEAs in complex samples. The proposed method displayed favorable linearity, low limits of detection (0.003 ~ 0.018 µg kg-1), and good repeatability (2.37~10.4%). The developed method has been applied for real sample analysis, with recoveries of 81.27~90.26%. These results showed that Fe3O4@TAPB-Tp has a good application potential for the adsorption of ZEAs in food samples. Magnetic covalent organic framework nanocomposite (Fe3O4@TAPB-Tp) were quickly fabricated at mild conditions and used as effective adsorbent for magnetic solid-phase extraction of zearalenone and its derivatives (ZEAs) from food samples prior to ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis.


Asunto(s)
Nanopartículas de Magnetita/química , Estructuras Metalorgánicas/química , Micotoxinas/análisis , Zearalenona/análisis , Adsorción , Animales , Derivados del Benceno/química , Cromatografía Líquida de Alta Presión , Huevos/análisis , Contaminación de Alimentos/análisis , Límite de Detección , Fenómenos Magnéticos , Leche/química , Micotoxinas/química , Micotoxinas/aislamiento & purificación , Nanocompuestos/química , Floroglucinol/análogos & derivados , Floroglucinol/química , Polimerizacion , Extracción en Fase Sólida/métodos , Espectrometría de Masas en Tándem , Zea mays , Zearalenona/análogos & derivados , Zearalenona/aislamiento & purificación
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