Reaction sites of pyrimidine bases and nucleosides during chlorination: A computational study.

As important components of soluble microbial products in water, nucleobases have attracted much attention due to the high toxicity of their direct aromatic halogenated disinfection by-products (AH-DBPs) during chlorination. However, multiple halogenation sites of AH-DBPs pose challenges to identify them. In this study, reaction sites of pyrimidine bases and nucleosides during chlorination were investigated by quantum chemical computational method. The results indicate that the anion salt forms play key roles in chlorination of uracil, thymine, and their nucleosides, while neutral forms make predominant contributions to cytosine and cytidine. In view of both kinetics and thermodynamics, C5 is the most reactive site for uracil and thymine, N3/C5 and N3 for respective uridine and thymidine, N1/C5/N4 and N4 for respective cytosine and cytidine, whose estimated apparent rate constants kobs-est of ∼103, 103/102, 106/102/104, and 103 M-1 s-1, respectively, in consistent with the known experimental results. C6 in all pyrimidine compounds is hardly attacked by Cl+ in HOCl ascribed to its positive charge, but readily attacked by OH‾ in hydrolysis and the N1=C6 bond was found to possess the highest reactivity in hydrolysis among all double bonds. In addition, the structure-kinetic reactivity relationship study reveals a relatively strong correlation between lgkobs-est and APT charge in all pyrimidine compounds rather than FED2 (HOMO). The results are helpful to further understand the reactivity of various reaction sites in aromatic compounds during chlorination.

Identification of reaction sites and chlorinated products of purine bases and nucleosides during chlorination: a computational study.

Hypochlorous acid (HOCl) released from activated leukocytes plays a significant role in the human immune system, but is also implicated in numerous diseases due to its inappropriate production. Chlorinated nucleobases induce genetic changes that potentially enable and stimulate carcinogenesis, and thus have attracted considerable attention. However, their multiple halogenation sites pose challenges to identify them. As a good complement to experiments, quantum chemical computation was used to uncover chlorination sites and chlorinated products in this study. The results indicate that anion salt forms of all purine compounds play significant roles in chlorination except for adenosine. The kinetic reactivity order of all reaction sites in terms of the estimated apparent rate constant kobs-est (in M-1 s-1) is heterocyclic NH/N (102-107) > exocyclic NH2 (10-2-10) > heterocyclic C8 (10-5-10-1), but the order is reversed for thermodynamics. Combining kinetics and thermodynamics, the numerical simulation results show that N9 is the most reactive site for purine bases to form the main initial chlorinated product, while for purine nucleosides N1 and exocyclic N2/N6 are the most reactive sites to produce the main products controlled by kinetics and thermodynamics, respectively, and C8 is a possible site to generate the minor product. The formation mechanisms of biomarker 8-Cl- and 8-oxo-purine derivatives were also investigated. Additionally, the structure-kinetic reactivity relationship study reveals a good correlation between lg kobs-est and APT charge in all purine compounds compared to FED2 (HOMO), which proves again that the electrostatic interaction plays a key role. The results are helpful to further understand the reactivity of various reaction sites in aromatic compounds during chlorination.

Research on the spatial temporary evolution of urban expansion in Xining city and its surrounding areas based on Landsat time series data.

Quantitative analysis of the process of urban expansion and evolution is of great practical significance for the future planning and development potential of valley cities. Based on GEE cloud platform and Landsat satellite data, this paper analyzed the spatio-temporal change characteristics and transfer rules of land cover in Xining City and its surrounding areas in the past 33 years by using random forest algorithm, spatio-temporal consistency test, land use dynamic attitude, transfer matrix and transfer hot spot analysis methods. The results show that the accuracy range of the preliminary classification of construction land is improved by 1.57%-3.53 % by using the spatio-temporal consistency test algorithm. The characteristics of land cover change in the study area are mainly the increase of construction land and forest area, the decrease of cultivated land and grassland area, the small change of water body and unused land, and the change of land cover type from cultivated land to urban construction land is prominent. The hot areas of construction land have gradually shifted from the central and eastern districts of the city in 1987 to the hot areas dominated by the Haihu New District of the West of the city, the Biological Park and the higher education base of the North District of the city, the South New District of the city, Duoba Town and the Ganhe Industrial Park in 2019.

Integrated metabolomics and network pharmacology to reveal antioxidant mechanisms and potential pharmacological ingredients of citrus herbs.

The benefits of citrus herbs are strongly associated with their secondary metabolites. In the study, we conducted widely-targeted metabolomics and ultra-high performance liquid chromatography (UPLC) to compare the variability of ingredients in four citrus herbs. In total, we discovered 1126 secondary metabolites, primarily comprising flavonoids, phenolic acids, lignans and coumarins, and alkaloids. Differential metabolites of citrus herbs were searched by multivariate statistical analysis. Notably, Citri Reticulatae Pericarpium contained higher levels of flavonoids, while Zhique and Huajuhong demonstrated a greater abundance of coumarins. Among the flavonoids determined by UPLC, Guangchenpi demonstrated significantly elevated levels of polymethoxyflavones (tangeretin and nobiletin) compared to other citrus herbs. Additionally, we determined their antioxidant capacity (Chenpi > Guangchenpi > Huajuhong > Zhique) using in vitro assays. Finally, we utilized network pharmacology to explore the antioxidant mechanisms and potential pharmacological ingredients, providing a basis for future preventive and therapeutic applications of these metabolites.

Temporal convolution network with a dual attention mechanism for φ-OTDR event classification.

We propose a hybrid model named channel attention based temporal convolutional network combined with spatial attention and bidirectional long short-term memory network (ATCN-SA-BiLSTM) for phase sensitive optical time domain reflectometry signal recognition. This hybrid model consists of three parts: ATCN, which extracts temporal features and preserves causality of time domain signals, the SA mechanism, which re-weights spatial sequences for better feature extraction, and BiLSTM, which extracts spatial relationships considering the bidirectional propagation characteristics of disturbances in space domain signals. Experimental results show that our method achieves better classification performance with an accuracy of 93.4% and zero nuisance alarm rate.

Machine learning methods for identification and classification of events in ϕ-OTDR systems: a review.

The phase sensitive optical time-domain reflectometer (φ-OTDR), or in some applications called distributed acoustic sensing (DAS), has been a popularly used technology for long-distance monitoring of vibrational signals in recent years. Since φ-OTDR systems usually operate in complicated and dynamic environments, there have been multiple intrusion event signals and also numerous noise interferences, which have been a major stumbling block toward the system's efficiency and effectiveness. Many studies have proposed different techniques to mitigate this problem mainly in φ-OTDR setup upgrades and improvements in data processing techniques. Most recently, machine learning methods for event classifications in order to help identify and categorize intrusion events have become the heated spot. In this paper, we provide a review of recent technologies from conventional machine learning algorithms to deep neural networks for event classifications aimed at increasing the recognition/classification accuracy and reducing nuisance alarm rates (NARs) in φ-OTDR systems. We present a comparative analysis of the current classification methods and then evaluate their performance in terms of classification accuracy, NAR, precision, recall, identification time, and other parameters.

NiMoFe/Cu nanowire core-shell catalysts for high-performance overall water splitting in neutral electrolytes.

A bifunctional NiMoFe/Cu NW core-shell catalyst assembled into a practical solar-driven overall water splitting system leads to an unprecedented solar-to-hydrogen (STH) efficiency of 10.99% in neutral electrolytes, attributed to the synergic combination of a unique 3D self-supported core-shell architecture and rapid electron/mass transfer properties.

Urinary polycyclic aromatic hydrocarbon metabolites, peripheral blood mitochondrial DNA copy number, and neurobehavioral function in coke oven workers.

BACKGROUND: Polycyclic aromatic hydrocarbons (PAHs) are the risk factors for workers' neurological performance, which were widely exist in the occupational environment. OBJECTIVE: We aimed to investigate the dose-response relationship between various PAH metabolites and workers' neurobehavioral changes and to explore whether mitochondrial DNA copy number (mtDNAcn) can be used as a potential biomarker to reflect changes in neurobehavioral behavior. METHOD: A total of 697 workers were recruited from a coke oven plant. The concentrations of eleven PAHs metabolites were determined by HPLC-MS/MS. Peripheral blood mtDNAcn was measured using QPCR. Neurobehavioral function was measured by NCTB questionnaire. The dose-response relationships were evaluated using restricted cubic spline models. Mediation analysis was also carried out. RESULTS: We found dose-response relationships between urinary 2-hydroxynaphthalene (2-OH Nap), sum of PAH metabolites (Æ© -OH PAHs) and total digit span (DSP), backward digit span (DSPB), forward digit span (DSPF) and mtDNAcn. Each one-unit increase in ln-transformed of 2-OH Nap or Æ© -OH PAHs was associated with a 2.64 or 3.22 decrease in DSP, a 1.20 or 1.58 decrease in DSPF, a 1.44 or 1.62 decrease in DSPB and a 0.13 or 0.12 decrease in mtDNAcn. However, we did not find a significant mediation effect of mtDNAcn between PAHs metabolites and DSP, DSPF, or DSPB. CONCLUSION: Our data indicated that workers urinary 2-hydroxynaphthalene and sum of PAH metabolites levels were inversely associated with mtDNAcn and neurobehavior, especially their auditory memory. However, there was no significant mediation effect of mtDNAcn between urinary PAHs metabolites and neurobehavior.

The associations between prenatal exposure to polycyclic aromatic hydrocarbon metabolites, umbilical cord blood mitochondrial DNA copy number, and children's neurobehavioral development.

Exposure to polycyclic aromatic hydrocarbons (PAHs) during pregnancy is a risk factor for adverse neurobehavioral development outcomes. Mitochondrial DNA are sensitive to environmental toxicants due to the limited ability of repairing. The change of mitochondrial DNA copy number (mtDNAcn) might be a biologically mechanism linking PAH exposure and children's neurobehavioral impairment. Our aims are to explore whether PAH metabolites in maternal urine were associated with children's neurobehavioral development at 2 years old and umbilical cord blood mtDNAcn, and whether mtDNAcn was a mediator of PAH-related neurobehavioral development. We included 158 non-smoking pregnant women from Taiyuan City, Shanxi Province. Maternal urinary eleven PAH metabolites were detected by high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). MtDNAcn in cord blood was detected by real time quantitative polymerase chain reaction (RT-PCR). Children's neurodevelopment was measured by Gesell Developmental Schedules (GDS) when children were two years age. Generalized linear models and restricted cubic spline models were applied to assess the relationships between PAH metabolites in maternal urine and GDS scores and mtDNAcn. A mediation analysis was also conducted. Generalized linear models showed the relationships of sum of PAH metabolites (Σ-OHPAHs) in maternal urine with decreased motor score, and Σ-OHPAHs with increased mtDNAcn (p for trend < 0.05). Urinary levels of Ln (Σ-OHPAHs) increased one unit was related to a 2.08 decreased in motor scores, and Ln (Σ-OHPAHs) increased one unit was related to 0.15 increased in mtDNAcn. Mediation analysis did not find mtDNAcn can be a mediator between PAH metabolites and neurobehavioral development. Our results suggest that prenatal exposure to PAH decreased children's neurobehavioral development scores and increased mtDNAcn. And reducing exposure to PAH during pregnancy will benefit to improving neurobehavioral development in children. In our present cohort study, sum of PAH metabolites in urine of pregnant women were related with motor score and were positively associated with umbilical cord blood mtDNA copy number.

Efficiently accumulating germ-like stem cells from mouse postnatal ovary by in situ tissue culture.

Although recent studies have revealed that germline stem cells (GSCs) exist in the mouse postnatal ovary, how to efficiently obtain GSCs for regenerating neo-oogenesis is still a technical challenge. Here, we report that using in situ tissue culture we can efficiently accumulate large amounts of proliferating germ-like cells from mouse postnatal ovaries. Usually, more than 10,000 germ-like cells can be derived from one ovary by this method, and over 20% of these cells can grow into germ-like cells with self-renewal, which thus can serve as a good cell pool to isolate GSCs by other cell assorting methods such as FACS. This method is simple and time-saving, which should be useful for in future studies on mouse GSCs.

In the human sperm nucleus, nucleosomes form spatially restricted domains consistent with programmed nucleosome positioning.

In human sperm, a fraction of its chromatin retains nucleosomes that are positioned on specific sequences containing genes and regulatory units essential for embryonic development. This nucleosome positioning (NP) feature provides an inherited epigenetic mark for sperm. However, it is not known whether there is a structural constraint for these nucleosomes and, if so, how they are localized in a three-dimensional (3D) context of the sperm nucleus. In this study, we examine the 3D organization of sperm chromatin and specifically determine its 3D localization of nucleosomes using structured illumination microscopy. A fraction of the sperm chromatin form nucleosome domains (NDs), visible as microscopic puncta ranging from 40 µm to 700 µm in diameter, and these NDs are precisely localized in the post acrosome region (PAR), outside the sperm's core chromatin. Further, NDs exist mainly in sperm from fertile men in a pilot survey with a small sample size. Together, this study uncovers a new spatially-restricted sub-nuclear structure containing NDs that are consistent with NPs of the sperm, which might represent a novel mark for healthy sperm in human.

Intravenous administration of adenosine triphosphate and phosphocreatine combined with fluoxetine in major depressive disorder: protocol for a randomized, double-blind, placebo-controlled pilot study.

BACKGROUND: Major depressive disorder (MDD) is a common psychiatric disorder. With systematic antidepressant treatment, 50-75% of patients have a treatment response but require 4-6 weeks to have their symptoms alleviated. Therefore, researchers anticipate the development of novel fast-acting antidepressants. Previous studies have revealed that the decrease of bio-energetic metabolism may contribute to the occurrence of depression, while our team has found adenosine triphosphate (ATP) and phosphocreatine (PCr) to be fast-acting antidepressants in the depressed-animal model. ATP and PCr have already been widely prescribed clinically as energy supplements for cells. This will be the first clinical attempt of the intravenous administration of ATP and PCr combined with orally administered fluoxetine in MDD. METHODS: This is a single-center, randomized, double-blind, placebo-controlled pilot study. A total of 42 patients will be divided randomly into three groups. Patients will receive an intravenous administration of ATP or PCr or saline twice daily combined with orally administered fluoxetine (20 mg/day) for the first 2 weeks and fluoxetine monotherapy for the following 4 weeks. Follow-up assessment will be completed at week 10. Feasibility outcomes will include percentages of patient eligibility, intention to use medication, willingness to participate, drug adherence, completion of the scheduled assessment, retention, drop-out, etc. Physical examination results, Side Effect Rating Scale, adverse events, results from blood tests, electroencephalogram, and electrocardiograph will be recorded for safety evaluation of the augmentation therapy. The trends of efficacy will be evaluated by the reduction rate of the Hamilton Depression Rating Scale, the mean change of the Clinical Global Impression Scale, and the Patients Health Questionaire-9 items. DISCUSSION: In our study, ATP and PCr will be given by intravenous infusion. Thus patients will be hospitalized for the initial 2 weeks for safety concern. Hospitalization will be an impact factor for the recruitment, participation, drop-out, efficacy, results, etc. The evaluation of our feasibility outcomes, study setting, safety of augmentation therapy and possible efficacy trends among groups, will facilitate a full-scale trial design and sample size calculation. TRIAL REGISTRATION: NCT03138681 . Registered on 3 May 2017. First patient: 4 May 2017.

Dissipation behavior of chlorpyrifos residues and risk assessment in sugarcane fields.

As chlorpyrifos is used globally to control pests in sugarcane fields, analysis of its residues on food crops is essential to assess product safety for humans. In this study, chlorpyrifos content in sugarcane plants, soil and juice was determined using a gas chromatography with an electron capture detector. The limit of quantification was 0.01 mg/kg for plant and soil, and 0.01 mg/L for juice. The degradation and residual risk in sugarcane fields after applying chlorpyrifos to two sample sites (Changsha and Danzhou, China) were assessed. Chlorpyrifos concentrations in plants and soil decreased rapidly over time, reaching a degradation rate ranging from 98.82 to 99.25% on day 35. The half-life of chlorpyrifos in both plants and soil was only 5.97-6.12 days. Regardless of application dosage (standard or high) at a pre-harvest interval of 60 days, chlorpyrifos was undetectable in the harvested sugarcane. Risk assessment indicated that chlorpyrifos residue in sugarcane did not pose a health risk to humans.

Transplanted human neural precursor cells integrate into the host neural circuit and ameliorate neurological deficits in a mouse model of traumatic brain injury.

Traumatic brain injury (TBI) is to date one of the major critical conditions causing death and disability worldwide. Exogenous neural stem/precursor cells (NSCs/NPCs) hold great promise for improving neurological dysfunction, but their functional properties in vivo remain unknown. Human neural precursor cells (hNPCs) carrying one fluorescent reporter gene (DsRed) can be observed directly in vivo using two-photon laser-scanning microscope. Therefore, we evaluated the neural integration and potential therapeutic effect of hNPCs on mice with TBI. Behavioral tests were performed by rotarod task and Morris Water Maze task. Neural integration was detected by fluorometric Ca2+ imaging and nerve tracing. We found that motor and cognition functions were significantly improved in mice with hNPCs injection compared to mice with vehicle treatment, and hNPCs integrated into the host circuit and differentiated toward neuronal lineage. Our study provided reliable evidence for further hNPCs transplantation in clinical practice.

Amphiphilic Functionalized Acupuncture Needle as SERS Sensor for In Situ Multiphase Detection.

Surface enhanced Raman spectroscopy (SERS) is a powerful spectroscopic technique with unique vibrational fingerprints, making it an ideal candidate for in situ multiphase detection. However, it is a great challenge to determine how to guide the SERS sensor to target molecules of interest in multiphase heterogeneous samples with minimal disturbance. Here, we present a portable ultrasensitive and highly repeatable SERS sensor for in situ multiphase detection. The sensor is composed of commercial Ag acupuncture needle and PVP-Au nanoparticles (Au NPs). The PVP on the Au NPs can adsorb and induce the Au NPs into a highly uniform array on the surface of the Ag needle because of its adhesiveness and steric nature. The Au NPs-Ag Needle system (Au-AgN) holds a huge SERS effect, which is enabled by the multiple plasmonic couplings from particle-film and interparticle. The PVP, as the amphiphilic polymer, promotes the target molecules to adsorb on surface of the Au-AgN whether in the oil phase or in the water phase. In this work, the Au-AgN sensor was directly inserted into the multiphase system with the laser in situ detection, and SERS detection at different spots of the Au-AgN sensor provided Raman signal of targets molecule in the different phase. In situ multiphase detection can minimize the disturbance of sampling and provide more accurate information. The facile fabrication and amphiphilic functionalization make Au-AgN sensor as generalized SERS detection platform for on-site testing of aqueous samples, organic samples, even the multiphase heterogeneous samples.

Real-time monitoring of plasmon-induced proton transfer of hypoxanthine in serum.

Intramolecular proton transfer of hypoxanthine, induced by application of a laser on the surface of a bare noble nanomaterial, was monitored in real time using surface-enhanced Raman spectroscopy (SERS). This monitoring demonstrated the dependence of the reaction on the identity of the nanomaterial and on the laser power density. The results pave the way for monitoring the proton transfer reaction in various relevant fields. In addition, we observed the presence of the proton transfer phenomenon of hypoxanthine in serum, providing a way to avoid the effect of proton transfer and hence achieve more reliable spectra of sera for clinical diagnosis.

Functionalized Acupuncture Needle as Surface-Enhanced Resonance Raman Spectroscopy Sensor for Rapid and Sensitive Detection of Dopamine in Serum and Cerebrospinal Fluid.

It is a challenge to develop a robust sensor for simple, rapid operation and sensitive detection of neurotransmitters in complex specimens. Herein, ferric citrate functionalized gold nanoparticles (CA-FeIII /Au NPs) are utilized to develop a facile sensor based on surface-enhanced resonance Raman spectroscopy (SERRS) for sensitive detection of dopamine (DA). The sensor is prepared by decorating the acupuncture needle with Au NPs, which enables sufficient surface-enhanced Raman spectroscopy enhancement. The CA-FeIII structure is highly sensitive and selective for DA due to the formation of the CA-FeIII -DA resonant structure; this indicates the advantages of capturing, carrying, and separating DA molecules from complicated samples in a simple operation. Furthermore, the practical application of the fabricated sensor is validated by the detection of DA in pretreated serum and cerebrospinal fluid of acupuncture-treated mice with detection limits of 0.1 and 2.5 nm DA, respectively. The developed active acupuncture needle sensor has potential benefits for sensitive detection and qualitative identification of DA molecules from biological samples.

[Research progress in supramolecular compounds-based stationary phases for capillary electrochromatography].

Supramolecular chemistry is a new branch of sciences, which deals with the specific recognitions between molecules. The host-guest interactions, which exert by supramolecular compounds, can provide a promising prospect for chromatographic separations with high selectivities. Capillary electrochromatography (CEC) is defined as a very promising micro-separation technique with high efficiency and high selectivity in recent years. As the key component of CEC, the stationary phases have been the research focus of CEC development. This paper reviews the recent progress in supramolecular compounds-based stationary phases (cyclodextrin, calixarene, crown ether and macrocyclic polyamine) for CEC since 1998.

[Function of F10 gene, a novel hydatidiform mole-related gene: a preliminary study].

OBJECTIVE: To study the function of F10 gene, a novel hydaditiform mole-related gene. METHODS: A549 cell line was transfected with the F10 gene of forward or reverse sequence or with the empty vector, respectively. The cellular mRNA was extracted after 24 h of transfection to screen for the differentially expressed genes among the 3 transfected and the control cells using differential display-polymerase chain reaction (ddPCR). RESULTS: The bands representing differentially expressed genes were amplified from the cells, and the products were linked to T-Vector for sequence analysis. Several genes were screened by Blasting and their expressions were confirmed by fluorescent quantitative PCR. CONCLUSION: F10 gene is functionally related to cell proliferation and apoptosis.