Recent trends in multidimensional countercurrent chromatography.

Countercurrent chromatography (CCC) is a potent separation approach known for its remarkable efficiency and capacity in preparation. It's applied as a substitute or combined with different chromatographic techniques, resulting in its rebranding as multidimensional CCC (MDCCC). Numerous essential mixtures from natural products contain hundreds or thousands of distinct components of importance. These mix types are too complicated to separate in any reasonable time using a single CCC dimension. However, if a multidimensional technique is utilized, where a complex mixture is separated by an initial dimension, smaller fractions of that separation are gathered. Each fraction is studied individually; complex mixes can be resolved relatively quickly. Thus, several MDCCC separation features have been studied to demonstrate their advantages, limitations, and prospective capacity to separate exceedingly complex mixtures. In this review, MDCCC aspects, including principles, multiple columns system, multilayer coil J-type, on-line monitoring system, and applications, have been thoroughly_explored.

Continuous chiral separation process for high-speed countercurrent chromatography established and scaled up: A case of Voriconazole enantioseparation.

An efficient method for the continuous separation of Voriconazole enantiomers was developed using sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD) as a chiral selector in high-speed countercurrent chromatography (HSCCC) with different types. The separation was performed using a two-phase solvent system consisting of n-hexane/ethyl acetate/100 mmol/L phosphate buffer solution (pH = 3.0, containing 50 mmol/L SBE-ß-CD) (1.5:0.5:2, v/v/v). A fast and predictable scale-up process was achieved using an analytical DE HSCCC instrument. The optimized parameters were subsequently applied to a preparative Tauto HSCCC instrument, resulting in consistent separation time and enantiomeric purity, with throughput boosted by a remarkable 11-fold. Preparative HSCCC successfully separated 506 mg of the racemate, delivering enantiomers exceeding 99% purity as confirmed by high-performance liquid chromatography analysis. This investigation presents an effective methodology for forecasting the HSCCC scale-up process and attaining continuous separation of chiral drugs.

Synthesis and Antimicrobial Activity Evaluation of Pyridine Derivatives Containing Imidazo[2,1-b][1,3,4]Thiadiazole Moiety.

Four series of novel pyridine derivatives (17 a-i, 18 a-i, 19 a-e, and 20 a-e) were synthesized and their antimicrobial activities were evaluated. Of all the target compounds, almost half target compounds showed moderate or high antibacterial activity. The 4-F substituted compound 17 d (MIC=0.5 µg/mL) showed the highest antibacterial activity, its activity was twice the positive control compound gatifloxacin (MIC=1.0 µg/mL). For fungus ATCC 9763, the activities of compounds 17 a and 17 d are equivalent to the positive control compound fluconazole (MIC=8 µg/mL). Furthermore, compounds 17 a and 17 d showed little cytotoxicity to human LO2 cells, and did not show hemolysis even at ultra-high concentration (200 µM). The results indicate that these compounds are valuable for further development as antibacterial and antifungal agents.

Parental Autonomy Granting, Peer Attachment and Problematic Internet Use Among Chinese Adolescents: The Moderating Effect of School Climate.

While the correlation between parental autonomy granting and adolescents' problematic Internet use (PIU) has been confirmed, the processes underlying this connection have not been thoroughly investigated. Drawing on the ecological systems theory, this study sought to investigate the mediating mechanism of peer attachment and the moderating mechanism of school climate that link parental autonomy granting to PIU. A two-wave longitudinal design was employed with a time interval of six months. The participants were 852 adolescents who attended three middle schools located in Guangdong Province, China. Self-report questionnaires were used to obtain data on demographics, parental autonomy granting, peer attachment, school climate, and PIU. The findings indicated that peer attachment significantly mediated the link between parental autonomy granting and adolescent PIU. A positive school climate significantly moderated the influence of parental autonomy granting on peer attachment and the influence of peer attachment on PIU. Specifically, the association between parental autonomy granting and peer attachment and the association between peer attachment and PIU were more pronounced when the school climate was perceived to be positive. This research underscores the possible significance of peer attachment in the association between parental autonomy granting and PIU and offers valuable insights for mitigating the negative outcomes of PIU.

A Nomogram Based on Nutrition-Related Indicators and Computed Tomography Imaging Features for Predicting Preoperative Lymph Node Metastasis in Curatively Resected Esophagogastric Junction Adenocarcinoma.

BACKGROUNDS: Preoperative noninvasive tools to predict pretreatment lymph node metastasis (PLNM) status accurately for esophagogastric junction adenocarcinoma (EJA) are few. Thus, the authors aimed to construct a nomogram for predicting PLNM in curatively resected EJA. METHODS: This study enrolled 638 EJA patients who received curative surgery resection and divided them randomly (7:3) into training and validation groups. For nomogram construction, 26 candidate parameters involving 21 preoperative clinical laboratory blood nutrition-related indicators, computed tomography (CT)-reported tumor size, CT-reported PLNM, gender, age, and body mass index were screened. RESULTS: In the training group, Lasso regression included nine nutrition-related blood indicators in the PLNM-prediction nomogram. The PLNM prediction nomogram yielded an area under the receiver operating characteristic (ROC) curve of 0.741 (95 % confidence interval [CI], 0.697-0.781), which was better than that of the CT-reported PLNM (0.635; 95% CI 0.588-0.680; p < 0.0001). Application of the nomogram in the validation cohort still gave good discrimination (0.725 [95% CI 0.658-0.785] vs 0.634 [95% CI 0.563-0.700]; p = 0.0042). Good calibration and a net benefit were observed in both groups. CONCLUSIONS: This study presented a nomogram incorporating preoperative nutrition-related blood indicators and CT imaging features that might be used as a convenient tool to facilitate the preoperative individualized prediction of PLNM for patients with curatively resected EJA.

Design, synthesis, and evaluation of 2,2'-bipyridyl derivatives as bifunctional agents against Alzheimer's disease.

Alzheimer's disease (AD) is a complex multifactorial neurodegenerative disease. Metal ion dyshomeostasis and Aß aggregation have been proposed to contribute to AD progression. Metal ions can bind to Aß and promote Aß aggregation, and ultimately lead to neuronal death. Bifunctional (metal chelation and Aß interaction) compounds are showing promise against AD. In this work, eleven new 3,3'-diamino-2,2'-bipyridine derivatives 4a-4k were synthesized, and evaluated as bifunctional agents for AD treatment. In vitro Aß aggregation inhibition assay confirmed that most of the synthesized compounds exhibited significant self-induced Aß1-42 aggregation inhibition. Among them, compound 4d displayed the best inhibitory potency of self-induced Aß1-42 aggregation with IC50 value of 9.4 µM, and it could selectively chelate with Cu2+ and exhibited 66.2% inhibition of Cu2+-induced Aß1-42 aggregation. Meanwhile, compound 4d showed strong neuroprotective activity against Aß1-42 and Cu2+-treated Aß1-42 induced cell damage. Moreover, compound 4d in high dose significantly reversed Aß-induced memory impairment in mice.

An overview of recent progress in multiple dual-mode counter-current chromatography.

Counter-current chromatography is a chromatographic separation and purification technique being developed. The development of different elution modes has significantly contributed to this field. Multiple dual-mode elution is a method developed based on dual-mode elution, which consists of a series of changing cycles of the phase role and the direction by switching between normal and reverse elution modes of counter-current chromatography. This dual-mode elution method takes full advantage of the liquid nature of stationary and mobile phases of counter-current chromatography and effectively improves the separation efficiency. So, this unique elution mode has gained extensive attention for separating complex samples. This review mainly describes and summarizes in detail its development, applications, and characteristics in recent years. Meanwhile, its advantages, limitations, and future outlook also have been discussed in this paper.

[Advantages, development opportunities, and practice paths of traditional Chinese medicine in prevention and treatment of elderly comorbidities].

This article focused on the significant public health issue of comorbidities in the elderly population and highlighted the important role of traditional Chinese medicine(TCM) in the prevention and treatment of comorbidities in the elderly. It suggested that TCM should fully utilize its advantages in holistic perspective, syndrome differentiation and treatment, and preventive medicine in the process of preventing and treating comorbidities in the elderly. At the same time, in response to the significant shift in the disease spectrum of the elderly, the increasingly innovative concepts in diagnosis and treatment, the growing demand for proactive health by the el-derly population, and the current emphasis on patient-centered evaluation standards, it is necessary to further conduct basic theoretical and experimental research on comorbidities in the elderly using TCM, emphasize clinical research on comorbidities in the elderly, explore appropriate efficacy evaluation systems, improve TCM prevention and treatment strategies and comprehensive intervention programs for comorbidities in the elderly, and leverage the unique role of TCM in the rehabilitation of elderly comorbidity patients. By analyzing the potential of TCM in the field of comorbidities in the elderly, this article is expected to provide new insights for future clinical practice and scientific research.

Rapid visual detection of porcine reproductive and respiratory syndrome virus via recombinase polymerase amplification combined with a lateral flow dipstick.

Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically devastating infectious diseases in the global swine industry. A rapid and sensitive on-site detection method for PRRS virus (PRRSV) is critically important for diagnosing PRRS. In this study, we established a method that combines reverse transcription recombinase polymerase amplification (RT-RPA) with a lateral flow dipstick (LFD) for detecting North American PRRSV (PRRSV-2). The primers and probe were designed based on the conserved region of all complete PRRSV-2 genomic sequences available in China (n = 512) from 1996 to 2020. The detection limit of the assay was 5.6 × 10-1 median tissue culture infection dose (TCID50) per reaction within 30 min at 42 °C, which was more sensitive than that of reverse transcription polymerase chain reaction (RT-PCR) (5.6 TCID50 per reaction). The assay was highly specific for the epidemic lineages of PRRSV-2 in China and did not cross-react with pseudorabies virus, porcine circovirus 2, classical swine fever virus, or porcine epidemic diarrhea virus. The assay performance was evaluated by testing 179 samples and comparing the results with those of quantitative RT-PCR (RT-qPCR). The results showed that the detection coincidence rate of RT-RPA and RT-qPCR was 100% when the cycle threshold values of RT-qPCR were < 32. The assay provides a new alternative for simple and reliable detection of PRRSV-2 and has great potential for application in the field.

A model for continuous sample feed and separation with counter-current chromatography based on elution-extrusion mode and its application.

A novel and meaningful theoretical model was established with counter-current chromatography based on the elution-extrusion mode for efficient continuous separation. For the experimental verification of the theory, the separation of the binary mixture luteolin/baicalein was studied. The velocity model and volume model of the chromatographic separation behavior of the target compounds in the separation process were given by theoretical analysis. The results showed that this method had obvious advantages in the separation of binary mixtures. In addition, the established model was used to predict and isolate oleuropein from olive leaves. A two-phase solvent system of n-butanol/ethyl acetate/methanol/water (1:19:1:19, v/v/v/v) was chosen for the continuous separation of oleuropein. After optimizing the conditions in this way, a large amount of sample loading was achieved; the volume of injections can reach 48 ml, approximately 35.29% of the volume of the counter-current chromatography column, and oleuropein with a purity of 86.42% was obtained within 80 min. The model provided technical support for the prediction of chromatographic behavior and operating parameters during continuous separation and preparation of counter-current chromatography. It has great application prospects and significance in separation preparation, especially in large-scale industrial preparation.

Role of three-phase solvent system in the counter-current chromatography.

In counter-current chromatography, the separation efficiency greatly depends on the partitioning ability of the separated substance between the stationary phase and the mobile phase. Partitioning ability is mainly represented by the parameter partition coefficient which is one of the important parameters to evaluate the separation effect of counter-current chromatography. The scope of the partition coefficient value mainly depends on the solvent system. A suitable solvent system election is, therefore, a critical role in the separation of counter-current chromatography. The existing solvent systems that are widely used are mainly two-phase solvent systems. It is difficult to decide on an appropriate solvent system for the separation of compounds with a wide polarity range, which promotes the development of the three-phase solvent system in counter-current chromatography. This review mainly described the origin, development history of three-phase solvent system, summarized the volume ratios and volume fractions of the upper, middle, and lower phases of nearly 50 three-phase solvent systems, their advantages, and disadvantages in counter-current chromatography. In addition, the challenges and future perspectives on three-phase solvent systems in counter-current chromatography also are discussed in this review.

Comprehensive separation of a wide variety of compounds from olive leaves by counter-current chromatography with three-phase solvent system.

The three-phase solvent system counter-current chromatography has been of great research interest, because it can separate compounds with a wide range of polarity. The solvent system of n-hexane/methyl tert-butyl ether/acetonitrile/water (5:5:7:5, v/v) was used for counter-current chromatographic comprehensive separation of olive leaves. The study adopted the normal elution mode. The middle phase and the lower phase (at a volume ratio of 7:3) were pumped into the column simultaneously, followed by eluting with the upper, middle, and lower phases in sequence. The retention rate of the stationary phase measured by the experiment was 73.5%. The upper phase was used to elute the nonpolar compounds, then the mobile phase was switched to the middle phase to elute the moderately hydrophobic compounds, finally, the polar compounds were eluted by the lower phase remaining in the chromatographic column. This method successfully separated eight compounds in one step within 270 min and five compounds were identified. The logP values of these five compounds were 7.44, 7.86, 4.16, -0.11, and 0.96, respectively, covering a wide range of polarities. The present study demonstrated that the three-phase solvent has a strong extraction capacity for ingredients from extremely hydrophilic compounds to extremely hydrophobic compounds.

Phylogenetics, Genomic Recombination, and NSP2 Polymorphic Patterns of Porcine Reproductive and Respiratory Syndrome Virus in China and the United States in 2014-2018.

Porcine reproductive and respiratory syndrome virus (PRRSV), an important pathogen that affects the pig industry, is a highly genetically diverse RNA virus. However, the phylogenetic and genomic recombination properties of this virus have not been completely elucidated. In this study, comparative analyses of all available genomic sequences of North American (NA)-type PRRSVs (n = 355, including 138 PRRSV genomes sequenced in this study) in China and the United States during 2014-2018 revealed a high frequency of interlineage recombination hot spots in nonstructural protein 9 (NSP9) and the GP2 to GP3 regions. Lineage 1 (L1) PRRSV was found to be susceptible to recombination among PRRSVs both in China and the United States. The recombinant major parent between the 1991-2013 data and the 2014-2018 data showed a trend from complex to simple. The major recombination pattern changed from an L8 to L1 backbone during 2014-2018 for Chinese PRRSVs, whereas L1 was always the major backbone for US PRRSVs. Intralineage recombination hot spots were not as concentrated as interlineage recombination hot spots. In the two main clades with differential diversity in L1, NADC30-like PRRSVs are undergoing a decrease in population genetic diversity, NADC34-like PRRSVs have been relatively stable in population genetic diversity for years. Systematic analyses of insertion and deletion (indel) polymorphisms of NSP2 divided PRRSVs into 25 patterns, which could generate novel references for the classification of PRRSVs. The results of this study contribute to a deeper understanding of the recombination of PRRSVs and indicate the need for coordinated epidemiological investigations among countries.IMPORTANCE Porcine reproductive and respiratory syndrome (PRRS) is one of the most significant swine diseases. However, the phylogenetic and genomic recombination properties of the PRRS virus (PRRSV) have not been completely elucidated. In this study, we systematically compared differences in the lineage distribution, recombination, NSP2 polymorphisms, and evolutionary dynamics between North American (NA)-type PRRSVs in China and in the United States. Strikingly, we found high frequency of interlineage recombination hot spots in nonstructural protein 9 (NSP9) and in the GP2 to GP3 region. Also, intralineage recombination hot spots were scattered across the genome between Chinese and US strains. Furthermore, we proposed novel methods based on NSP2 indel patterns for the classification of PRRSVs. Evolutionary dynamics analysis revealed that NADC30-like PRRSVs are undergoing a decrease in population genetic diversity, suggesting that a dominant population may occur and cause an outbreak. Our findings offer important insights into the recombination of PRRSVs and suggest the need for coordinated international epidemiological investigations.

Recovery and recycling of solvent of counter-current chromatography: The sample of isolation of zeaxanthin in the Lycium barbarum L. fruits.

An efficient method of recovering and recycling solvent for counter-current chromatography was established by which zeaxanthin was separated from Lycium barbarum L. fruits. A column with activated carbon combined with high performance counter-current chromatography formed the recovering and recycling solvent system. Using the solvent system of n-hexane-ethyl acetate-ethanol-water (8:2:7:3, v/v) from the references, five injections were performed with an almost unchanged purity of zeaxanthin (80.9, 81.2, 81.5, 81.3, and 80.2% respectively) in counter-current chromatography separation. Meanwhile, the mobile phase reduced by half than conventional counter-current chromatography. By this present method, an effective improvement of counter-current chromatography solvent utilization was achieved.

Chiral counter-current chromatography: A survey of its instrument, mechanism, procedure, and applications.

The chiral separation by counter-current chromatography has made great progress in the past three decades. It has become increasingly popular in the field of chiral separation, and many applications have been introduced during the last years. This review mainly focuses on the current topics, applications, and trends in chiral separation by counter-current chromatography. It contains the development of modern counter-current chromatography apparatus, theory of counter-current chromatography, overview of applications of chiral counter-current chromatography enantioseparation, its current situation, and challenges. At last, some conclusions and perspectives also have been discussed in this review.

Full use of the liquid nature of the stationary phase: The development of elution-extrusion counter current chromatography.

Elution-extrusion counter current chromatography extrudes the most solute retained in the column with the highest possible peak resolution. It can greatly improve the hydrophobic window. In recent years, elution-extrusion counter current chromatography has received extensive attention in the separation of complex samples. This article first reviews the development and application of elution-extrusion counter current chromatography, including its origin, mechanism, advantages and disadvantages, and some representative applications. At the same time, this review also shared our visions and ideas on how to improve the elution-extrusion mode. This article aims to provide certain reference for the research of this technology.

Effective on-line high-speed shear dispersing emulsifier technique coupled with high-performance countercurrent chromatography method for simultaneous extraction and isolation of carotenoids from Lycium barbarum L. fruits.

An efficient combination strategy based on high-speed shear dispersing emulsifier technique and high-performance countercurrent chromatography was developed for on-line extraction and isolation of carotenoids from the fruits of Lycium barbarum. In this work, the high-speed shear dispersing emulsifier technique has been employed to extract crude extracts using the upper phase of high-performance countercurrent chromatography solvent system composed of n-hexane-dichloromethane-acetonitrile (10:4:6.5, v/v) as the extraction solvent. At the separation stage, the high-performance counter-current chromatography process adopts elution-extrusion mode and the upper phase of the solvent system as stationary phase (reverse-phase mode). As a result, three compounds including zeaxanthin, zeaxanthin monopalmitate, and zeaxanthin dipalmitate with purities of 89, 90, and 93% were successfully obtained in one extraction-separation operation within 120 min. The targeted compounds were analyzed and identified by high-performance liquid chromatography, mass spectrometry, and NMR spectroscopy. The results indicated that the present on-line combination method could serve as a simple, rapid, and effective way to achieve weak polar and unstable compounds from natural products.

miRTarBase update 2018: a resource for experimentally validated microRNA-target interactions.

MicroRNAs (miRNAs) are small non-coding RNAs of ∼ 22 nucleotides that are involved in negative regulation of mRNA at the post-transcriptional level. Previously, we developed miRTarBase which provides information about experimentally validated miRNA-target interactions (MTIs). Here, we describe an updated database containing 422 517 curated MTIs from 4076 miRNAs and 23 054 target genes collected from over 8500 articles. The number of MTIs curated by strong evidence has increased ∼1.4-fold since the last update in 2016. In this updated version, target sites validated by reporter assay that are available in the literature can be downloaded. The target site sequence can extract new features for analysis via a machine learning approach which can help to evaluate the performance of miRNA-target prediction tools. Furthermore, different ways of browsing enhance user browsing specific MTIs. With these improvements, miRTarBase serves as more comprehensively annotated, experimentally validated miRNA-target interactions databases in the field of miRNA related research. miRTarBase is available at http://miRTarBase.mbc.nctu.edu.tw/.

Combined detection of serum autoantibodies as diagnostic biomarkers in esophagogastric junction adenocarcinoma.

BACKGROUND: We previously found that autoantibodies against a panel of six tumor-associated antigens (p53, NY-ESO-1, MMP-7, Hsp70, PRDX6 and Bmi-1) may aid in early detection of esophageal squamous cell carcinoma. Here we aimed to evaluate the diagnostic value of this autoantibody panel in esophagogastric junction adenocarcinoma (EJA) patients. METHODS: Serum autoantibody levels were measured by enzyme-linked immunosorbent assay in a training cohort and a validation cohort. We used receiver-operating characteristics (ROC) to calculate diagnostic accuracy. RESULTS: We recruited 169 normal controls and 122 EJA patients to the training cohort, and 80 normal controls and 70 EJA patients to the validation cohort. Detection of the autoantibody panel demonstrated an area under the curve (AUC) of 0.818, sensitivity 59.0% and specificity 90.5% in training cohort, and AUC 0.815, sensitivity 61.4% and specificity 90.0% in validation cohort in the diagnosis of EJA. Measurement of the autoantibody panel could distinguish early stage EJA patients from normal controls (AUC 0.786 and 0.786, sensitivity 50.0% and 56.0%, and specificity 90.5% and 90.0%, for training and validation cohorts, respectively). Moreover, a restricted panel consisting of autoantibodies against p53, NY-ESO-1 and Bmi-1 exhibited similar diagnostic performance for EJA (AUC 0.814 and 0.823, sensitivity 53.5% and 60.0%, and specificity 90.5% and 93.7%, for training and validation cohorts, respectively) and early stage EJA (AUC 0.744 and 0.773, sensitivity 55.6% and 52.0%, and specificity 90.5% and 93.7%, for training and validation cohorts, respectively). CONCLUSIONS: Autoantibodies against an optimized TAA panel as serum biomarkers appear to help identify the present of early stage EJA.

Continuous separation of maslinic and oleanolic acids from olive pulp by high-speed countercurrent chromatography with elution-extrusion mode.

In this work, a continuous high-speed countercurrent chromatography method has been developed on the basis of elution-extrusion mode and this method was successfully applied to the separation of maslinic and oleanolic acid from the extract of olive pulp. In the process of 'elution', the sample solution was continuously loaded into the column and the maslinic acid was steadily eluted out in this step while highly retained oleanlic acid always stayed in the column. In the process of 'extrusion', the oleanlic acid was pushed out of the column with the stationary phase. In this way, we achieved a large sample loading. A total of 120 mL sample solution (about 89.55% of the column volume) which contains 600 mg olive pulp extract was pumped in the apparatus by a constant-flow pump and the maslinic and oleanolic acids were largely separated within 120 min. Both of these two compounds presented high yields and high purities (271.6 mg for maslinic acid with 86.7% and 83.9 mg oleanolic acids with 83.4%).