A Critical Review of Groundwater Table Fluctuation: Formation, Effects on Multifields, and Contaminant Behaviors in a Soil and Aquifer System.

The groundwater table fluctuation (GTF) zone is an important medium for the hydrologic cycle between unsaturated soil and saturated aquifers, which accelerates the migration, transformation, and redistribution of contaminants and further poses a potential environmental risk to humans. In this review, we clarify the key processes in the generation of the GTF zone and examine its links with the variation of the hydrodynamic and hydrochemistry field, colloid mobilization, and contaminant migration and transformation. Driven by groundwater recharge and discharge, GTF regulates water flow and the movement of the capillary fringe, which further control the advection and dispersion of contaminants in soil and groundwater. In addition, the formation and variation of the reactive oxygen species (ROS) waterfall are impacted by GTF. The changing ROS components partially determine the characteristic transformation of solutes and the dynamic redistribution of the microbial population. GTF facilitates the migration and transformation of contaminants (such as nitrogen, heavy metals, non-aqueous phase liquids, and volatile organic compounds) through colloid mobilization, the co-migration effect, and variation of the hydrodynamic and hydrochemistry fields. In conclusion, this review illustrates the limitations of the current literature on GTF, and the significance of GTF zones in the underground environment is underscored by expounding on the future directions and prospects.

Prussian blue analogues derived magnetic FeCo@GC material as high-performance metallic peroxymonosulfate activators to degrade tetrabromobisphenol A over a wide pH range.

Metal-organic frame (MOF) materials can effectively degrade organic pollutants, whereas the MOF is rapidly hydrolysed in water and has poor stability and low reusability. However, in the current advanced oxidation process (AOP) system, the removal effect of pollutants under alkaline condition is not ideal. In this study, a magnetic composite material derived from MOF was synthesised and used as a new catalyst for rapid degradation of tetrabromobisphenol A (TBBPA). Compared to precarbonisation, FeCo@GC formed a conductive graphite carbon skeleton, retained the complete rhombododecahedron structure, had a larger specific surface area and provided more active sites for peroxymonosulfate (PMS) activation. The target pollutant TBBPA (20 mg/L) was completely degraded within 30 min, and the mineralisation rate reached 40.98% in the FeCo@GC (150 mg/L) and PMS (1 mM) systems, owing to the synergistic interaction between Fe, Co and graphite carbon. The reactive oxygen species (ROS) involved in the reaction were determined to be SO4•-, ·OH, 1O2 and O2•- by electron paramagnetic resonance and free radical scavenging experiments, and the 1O2 played a dominant role. Based on the results of LC-MS analysis results, the main degradation pathways of TBBPA involve three mechanisms: the debromination reaction, hydroxylation and cleavage of the benzene ring. In addition, compared with previous AOP systems, FeCo@GC/PMS overcomes the disadvantage of poor degradation effect of TBPPA under alkaline conditions, has a wide range pH (3-11) application and has the best effect on TBBPA degradation under alkaline conditions. FeCo@GC has an excellent cycle performance, with a removal rate of re-calcined material of 88.52% after five cycles. Therefore, FeCo@GC can be used as a promising and efficient catalyst for removing environmental organic pollutants.

Transcriptomic analysis of spinal cord regeneration after injury in Cynops orientalis.

Cynops orientalis (C. orientalis) has a pronounced ability to regenerate its spinal cord after injury. Thus, exploring the molecular mechanism of this process could provide new approaches for promoting mammalian spinal cord regeneration. In this study, we established a model of spinal cord thoracic transection injury in C. orientalis, which is an endemic species in China. We performed RNA sequencing of the contused axolotl spinal cord at two early time points after spinal cord injury - during the very acute stage (4 days) and the subacute stage (7 days) - and identified differentially expressed genes; additionally, we performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses, at each time point. Transcriptome sequencing showed that 13,059 genes were differentially expressed during C. orientalis spinal cord regeneration compared with uninjured animals, among which 4273 were continuously down-regulated and 1564 were continuously up-regulated. Down-regulated genes were most enriched in the Gene Ontology term "multicellular organismal process" and in the ribosome pathway at 10 days following spinal cord injury. We found that multiple genes associated with energy metabolism were down-regulated and multiple genes associated with the lysosome were up-regulated after spinal cord injury, indicating the importance of low metabolic activity during wound healing. Immune response-associated pathways were activated during the early acute phase (4 days), while the expression of extracellular matrix proteins such as glycosaminoglycan and collagen, as well as tight junction proteins, was lower at 10 days post-spinal cord injury than 4 days post-spinal cord injury. However, compared with 4 days post-injury, at 10 days post-injury neuroactive ligand-receptor interactions were no longer down-regulated, up-regulated differentially expressed genes were enriched in pathways associated with cancer and the cell cycle, and SHH, VIM, and Sox2 were prominently up-regulated. Immunofluorescence staining showed that glial fibrillary acidic protein was up-regulated in axolotl ependymoglial cells after injury, similar to what is observed in mammalian astrocytes after spinal cord injury, even though axolotls do not form a glial scar during regeneration. We suggest that low intracellular energy production could slow the rapid amplification of ependymoglial cells, thereby inhibiting reactive gliosis, at early stages after spinal cord injury. Extracellular matrix degradation slows cellular responses, represses the expression of neurogenic genes, and reactivates a transcriptional program similar to that of embryonic neuroepithelial cells. These ependymoglial cells act as neural stem cells: they migrate and proliferate to repair the lesion and then differentiate to replace lost glial cells and neurons. This provides the regenerative microenvironment that allows axon growth after injury.

CDK5RAP3, a key defender of udder, modulates NLRP3 inflammasome activation by regulating autophagolysosome degradation in S. agalactiae-infected mastitis.

Streptococcus agalactiae, as one of the main pathogens of clinical and subclinical mastitis, affects animal welfare and leads to huge economic losses to farms due to the sharp decline in milk yield. However, both the real pathogenic mechanisms of S. agalactiae-induced mastitis and the regulator which controls the inflammation and autophagy are largely unknown. Served as a substrate of ubiquitin-like proteins of E3 ligase, CDK5RAP3 is widely involved in the regulation of multiple signaling pathways. Our findings revealed that CDK5RAP3 was significantly down-regulated in mastitis infected by S. agalactiae. Surprisingly, inflammasome activation was triggered by CDK5RAP3 knockdown: up-regulated NLRP3, IL1ß and IL6, and cleaved caspase1 promoting by NF-κB, thereby resulting in pyroptosis. Additionally, the accumulation of autophagy markers (LC3B and p62) after CDK5RAP3 knockdown suggested that the autophagolysosome degradation pathway was inhibited, thereby activating the NF-κB pathway and NLRP3 inflammasome. Hence, our findings suggest that downregulation or ablation of CDK5RAP3 inhibits autophagolysosome degradation, causes inflammation by activating the NF-κB /NLRP3 inflammasome, and triggers cell death. In conclusion, CDK5RAP3 holds the key to understanding the interaction between autophagy and immune responses, its anti-inflammatory role in this study will throw new light on the clinical drug discovery to cure S. agalactiae mastitis.

UFL1, a UFMylation E3 ligase, plays a crucial role in multiple cellular stress responses.

The UFM1 conjugation system(UFMylation)is a novel type of ubiquitin-like system that plays an indispensable role in maintaining cell homeostasis under various cellular stress. Similar to ubiquitination, UFMylation consists of a three-step enzymatic reaction with E1-like enzymes ubiquitin-like modifier activating enzyme5 (UBA5), E2-like enzymes ubiquitin-fold modifier-conjugating enzyme 1(UFC1), and E3-like ligase UFM1-specific ligase 1 (UFL1). As the only identified E3 ligase, UFL1 is responsible for specific binding and modification of the substrates to mediate numerous hormone signaling pathways and endocrine regulation under different physiological or pathological stress, such as ER stress, genotoxic stress, oncogenic stress, and inflammation. Further elucidation of the UFL1 working mechanism in multiple cellular stress responses is essential for revealing the disease pathogenesis and providing novel potential therapeutic targets. In this short review, we summarize the recent advances in novel UFL1 functions and shed light on the potential challenges ahead, thus hopefully providing a better understanding of UFMylation-mediated cellular stress.

Triphenyl phosphate induced reproductive toxicity through the JNK signaling pathway in Caenorhabditis elegans.

Triphenyl phosphate (TPHP) is a widely used aryl organophosphate flame retardant (OPFR) that has attracted attention due to its frequent detection in the environment and living organisms. To date, the reproductive toxicity of TPHP has been investigated in organisms, but its molecular mechanisms are not fully understood. Caenorhabditis elegans (C. elegans) is the ideal animal for the study of reproductive toxicity following environmental pollutants, with short generation times, intact reproductive structures, and hermaphroditic fertilization. This study aimed to explore the reproductive dysfunction and molecular mechanisms induced by TPHP exposure in C. elegans. Specifically, exposure to TPHP resulted in a reduction in the number of eggs laid and developing embryos in utero, an increase in the number of apoptotic gonadal cells, and germ cell cycle arrest. The JNK signaling pathway is a potential pathway inducing reproductive toxicity following TPHP exposure based on transcriptome sequencing (RNA-seq). Moreover, TPHP exposure induced down-regulation of vhp-1 and kgb-2 gene transcription levels, and the knockout of vhp-1 and kgb-2 in the mutant strains exhibited more severe toxicity in apoptotic gonad cells, embryos, and eggs developing in utero, suggesting that vhp-1 and kgb-2 genes play a crucial role in TPHP-induced reproductive toxicity. Our data provide convergent evidence showing that TPHP exposure results in reproductive dysfunction through the JNK signaling pathway and improve our understanding of the ecotoxicity and toxicological mechanisms of aryl-OPFRs.

Review of the toxicity and potential molecular mechanisms of parental or successive exposure to environmental pollutants in the model organism Caenorhabditis elegans.

Environmental pollutants such as heavy metals, nano/microparticles, and organic compounds have been detected in a wide range of environmental media, causing long-term exposure in various organisms and even humans through breathing, contacting, ingestion, and other routes. Long-term exposure to environmental pollutants in organisms or humans promotes exposure of offspring to parental and environmental pollutants, and subsequently results in multiple biological defects in the offspring. This review dialectically summarizes and discusses the existing studies using Caenorhabditis elegans (C. elegans) as a model organism to explore the multi/transgenerational toxicity and potential underlying molecular mechanisms induced by environmental pollutants following parental or successive exposure patterns. Parental and successive exposure to environmental pollutants induces various biological defects in C. elegans across multiple generations, including multi/transgenerational developmental toxicity, neurotoxicity, reproductive toxicity, and metabolic disturbances, which may be transmitted to progeny through reactive oxygen species-induced damage, epigenetic mechanisms, insulin/insulin-like growth factor-1 signaling pathway. This review aims to arouse researchers' interest in the multi/transgenerational toxicity of pollutants and hopes to explore the possible long-term effects of environmental pollutants on organisms and even humans, as well as to provide constructive suggestions for the safety and management of emerging alternatives.

Iron-sulphur transformation control for enhancing Cr(VI) removal in flake and nanoscale porous pyrrhotite (Fe7S8) added wastewater.

Hexavalent chromium (Cr(VI)) contaminated wastewater should be addressed efficiently in the environmental field. In previous applications, nano iron sulfides amendment has not been well controlled for iron-sulfur transformation. In this study, the novel flake and nanoscale porous pyrrhotite (Fe7S8) (FNPP) amendment was synthesized. The iron-sulphur transformation of FNPP was controlled and optimized for enhancing Cr(VI) removal. The specific surface area and average pore diameter of the FNPP amendment reached 115.7 m2/g and 2.1 nm. The maximum adsorption capacity of total chromium reached 66.3 mg/g. The optimized iron-sulphur transformation condition was an initial FNPP and Cr(VI) molar ratio of 8, pH at 5.6, in which the Cr(VI) removal reached 96.5% and all producing S2- was utterly consumed. It is confirmed that S2- fast induced Fe3+/Fe2+ circulation and FNPP has a speedier adsorption rate for Cr(III) than Cr(VI). Fe2+ and S2- mediated the Cr(VI) reduction to Cr(III), thus, much faster Cr(VI) removal was achieved. High efficiency removal mechanism of Cr(VI) was combined with surface adsorption/reduction and solution reduction/precipitation. The research demonstrated that controlling and optimizing the iron-sulphur transformation of Fe7S8 amendment can significantly enhance Cr(VI) removal.

Plasmonic Bi promotes the construction of Z-scheme heterojunction for efficient oxygen molecule activation.

Reactive oxygen species (ROS) are essential to photocatalytic degradation of antibiotics in water. In this work, we prepared Ag3PO4/Bi@Bi4Ti3O12 by simple in-situ reduction method and precipitation method, which improves the ability to capture visible light and increases the activity of photoinduced molecular oxygen activation, resulting in reactive oxygen species (ROS) such as superoxide radicals (•O2-), hydroxyl radicals (•OH), and H2O2. The excellent TC degradation efficiency derive from the SPR effect of the metal Bi on the surface enhances the light absorption intensity, and development of a Z-scheme heterojunction between Ag3PO4 and Bi4Ti3O12 promotes the activation of molecular oxygen. A possible photodegradation mechanism of the as-prepared photocatalyst was proposed. This work provides an insight perspective to the synthesis photocatalysts with molecular oxygen activation for environmental remediation.

Nanoanalysis of the leaching process simulation of Pb in agricultural soil.

Using the Spectral characteristics of gold nanorods to investigate heavy metals Pb in agricultural soils. Studied included: (1) The effects of humic acid on Pb transformation and its formation changing were explored. The laboratory model was established to simulate Pb leaching process in the soil and investigated the change of total Pb content at different layers. (2) The migration and transformation of different forms Pb were studied by the nano system. The effect of humic acid and pH were analyzed based on the nano-analysis method. (3) The relationship between various forms Pb irons were analyzed. (4) The data showed that ion exchange state and iron-manganese oxidation state Pb were more likely to enriched at 0 cm depth, and organic bound state was more likely to enriched at 10 cm depth. Humic acid increased the solidify ability of different forms of Pb in agricultural soil, and the analysis system was efficient to supply the exactly transition process.

Humic acid promoted activation of peroxymonosulfate by Fe3S4 for degradation of 2,4,6-trichlorophenol: An experimental and theoretical study.

Chlorophenols are difficult to degrade and biohazardous in the natural environment. This study demonstrated that humic acid (HA) could promote Fe3S4 activation of peroxymonosulfate (PMS) to degrade 2,4,6-trichlorophenol (TCP), the degradation efficiency of TCP was increased by 33%. The system of Fe3S4-HA/PMS produced more reactive oxygen species, and •OH was the dominant ROS. The genealogy of iron oxides together with S0 on the Fe3S4 surface inhibited PMS activation leading to the significant reduction of TCP degraded (< 70%). These problems could be solved successfully through introducing HA, which facilitated electron transfer and increased the continuous release of iron ions by 2 times. In accordance with the determined density functional theory (DFT), the degradation pathway was put forward, which indicated that TCP dechlorination and oxidation to 2,6-dichloro-1,4-benzoquinone constituted the main degradation pathway. Furthermore, the intermediates that were produced in the main degradation processes of TCP showed lower toxicity than TCP according to results that were obtained utilizing the calculations of quantitative structure-activity relationship (QSAR) together with Toxicity Estimation Software Tool (TEST). Thus, the Fe3S4-HA/PMS system was demonstrated to be an efficient and safe technology for organic pollutant degradation in contaminated groundwater and surface water environments.

A Novel TLR4-SYK Interaction Axis Plays an Essential Role in the Innate Immunity Response in Bovine Mammary Epithelial Cells.

Mammary gland epithelium, as the first line of defense for bovine mammary gland immunity, is crucial in the process of mammary glands' innate immunity, especially that of bovine mammary epithelial cells (bMECs). Our previous studies successfully marked SYK as an important candidate gene for mastitis traits via GWAS and preliminarily confirmed that SYK expression is down-regulated in bMECs with LPS (E. coli) stimulation, but its work mechanism is still unclear. In this study, for the first time, in vivo, TLR4 and SYK were colocalized and had a high correlation in mastitis mammary epithelium; protein−protein interaction results also confirmed that there was a direct interaction between them in mastitis tissue, suggesting that SYK participates in the immune regulation of the TLR4 cascade for bovine mastitis. In vitro, TLR4 also interacts with SYK in LPS (E. coli)-stimulated or GBS (S. agalactiae)-infected bMECs, respectively. Moreover, TLR4 mRNA expression and protein levels were little affected in bMECsSYK- with LPS stimulation or GBS infection, indicating that SYK is an important downstream element of the TLR4 cascade in bMECs. Interestingly, IL-1ß, IL-8, NF-κB and NLRP3 expression in LPS-stimulated or GBS-infected bMECsSYK- were significantly higher than in the control group, while AKT1 expression was down-regulated, implying that SYK could inhibit the IL-1ß, IL-8, NF-κB and NLRP3 expression and alleviate inflammation in bMECs with LPS and GBS. Taken together, our solid evidence supports that TLR4/SYK/NF-κB signal axis in bMECs regulates the innate immunity response to LPS or GBS.

Tris(1,3-dichloro-2-propyl) phosphate reduces longevity through a specific microRNA-mediated DAF-16/FoxO in an unconventional insulin/insulin-like growth factor­1 signaling pathway.

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) has received concerns due to its frequent detection in environmental media and biological samples. Our previous study has indicated TDCPP reduced the lifespan of Caenorhabditis elegans (C. elegans) by triggering an unconventional insulin/insulin-like growth factor signaling (IIS) pathway. This study continued to investigate the possible deleterious effects of TDCPP relating to longevity regulation signal pathways and biological processes. Specifically, this study uniquely performed small RNA transcriptome sequencing (RNA-seq), focusing on the underlying mechanisms of TDCPP-reduced the longevity of C. elegans in-depth in microRNAs (miRNAs). Based on Small RNA-seq results and transcript levels of mRNA involved in the unconventional IIS pathway, a small interaction network of miRNAs-mRNAs following TDCPP exposure in C. elegans was preliminarily established. Among them, up-regulated miR-48 and miR-84 (let-7 family members) silence the mRNA of daf-16 (the crucial member of the FoxO family and pivotal regulator in longevity) via post-transcription and translation dampening abilities, further inhibit its downstream target metallothionein-1 (mtl-1), and ultimately contributed to the reduction of nematode longevity and locomotion behaviors. Meanwhile, the high binding affinities of TDCPP with miRNAs cel-miR-48-5p and cel-miR-84-5p strongly support their participation in the regulation of nematode mobility and longevity. These findings provide a comprehensive analysis of TDCPP-reduced longevity from the perspective of miRNAs.

Interaction quantitative modeling of mixed surfactants for synergistic solubilization by resonance light scattering.

In situ flushing through surfactant-enhanced aquifer remediation (SEAR) technology has long been recognized as a promising technique for NAPL removal from contaminated aquifers. However, there have been few studies on the choice of surfactants. In this work, the interaction quantitative model between resonance light scattering intensity and the concentration of binary surfactant mixtures NP-10+SDBS and NP-10+CTAB was established, and the mechanism of binary surfactant interaction was explored through the model by the resonance light scattering method. The relationship between the model constants and NAPL solubilization was also investigated to better address the application of surfactants in practical NAPL-contaminated site remediation. The critical micelle concentrations (CMCs) of nonylphenol ethoxylate (NP-10), dodecyl benzene sulfonate (SDBS), hexadecyl trimethyl ammonium bromide (CTAB), and the binary surfactant mixtures were measured by resonance light scattering (RLS), which were consistent with those obtained from surface tension measurements. In all cases, the RLS signals exhibited similar variations with surfactant concentration. A quantitative calculation model based on the RLS measurement data was established, and the binding constants KNP-10+SDBS and KNP-10+CTAB were calculated to be 0.66 and 1.51 L·mmol-1, respectively, according to the equilibrium equations. The results showed that the binding constants have a significant positive correlation with NAPL solubilization.

Carbon nanotubes mediating nano α-FeOOH reduction by Shewanella putrefaciens CN32 to enhance tetrabromobisphenol A removal.

Carbon nanotubes (CNTs) mediation of the reduction of nano goethite (α-FeOOH) by Shewanella putrefaciens CN32 to improve the removal efficiency of tetrabromobisphenol A (TBBPA) was investigated in this study. The results showed that CNTs effectively promoted the biological reduction of α-FeOOH by strengthening the electron transfer process between Shewanella putrefaciens CN32 and α-FeOOH. After α-FeOOH was reduced to Fe(II), the adsorbed Fe(II) accounted for approximately 69.07% of the total Fe(II). And the secondary mineral vivianite was formed during the reduction of α-FeOOH, which was determined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The vivianite (FeII3(PO4)2·8H2O) was formed by the reaction of PO43- and Fe(II). The degradation effect of TBBPA was the best at pH 8. CNT-α-FeOOH reduced the toxicity of TBBPA to CN32 and had good stability and reusability. The byproduct bisphenol A was detected which indicated that the degradation pathway of TBBPA involved reductive debromination. Electrochemical experiments and EPR analysis showed that the electron transfer capacities (ETC) of CNTs was an important factor in the removal of TBBPA, and it may greatly depend on semiquinone radicals (CO). This study provided a new method and theoretical support for the removal of TBBPA in the environment.

Chlorogenic acid inhibits forming of diabetes mellitus in rats induced by high-fat high-sucrose and streptozotocin.

To evaluate the inhibitory effect of chlorogenic acid on the forming of type 2 diabetes mellitus (T2DM), using Sprague Dawley (SD) rats, a recognized T2DM model induced by high-fat high-sucrose diet (HFSD) and streptozotocin (STZ). Thirty female SD rats were assigned equally to three groups randomly: normal control with standard commercial (NC), chlorogenic acid treatment with HFSD and chlorogenic acid (90mg/kg, CA), and diabetes model with HFSD (DM). Upon treatment with chlorogenic acid, suppression of the onset of diabetes, reduced serum glucose and insulin concentrations, improved glucose tolerance and increased body weight and visceral fat weight were observed. Serum triglyceride, total cholesterol, low density lipoprotein levels, and kidney and pancreas morphology were significantly ameliorated. Chlorogenic acid also inhibited the mRNA levels of hepatic G-6-Pase and up-regulated the mRNA levels of skeletal muscle GLUT4. Our results indicated that before the onset of diabetes, chlorogenic acid had an inhibitory effect against the forming of T2DM induced by HFSD and STZ through regulating the glucose and lipid metabolism.

A measurement method of knee joint space width by ultrasound: a large multicenter study.

BACKGROUND: Although plain radiology is the primary method for assessing joint space width (JSW), it has poor sensitivity to change over time in regards to determining longitudinal progression. We, therefore, developed a new ultrasound (US) measurement method of knee JSW and aimed to provide a monitoring method for the change of JSW in the future. METHODS: A multicenter study was promoted by the Professional Committee of Musculoskeletal Ultrasound, the Ultrasound Society, and the Chinese Medical Doctor Association. US study of knee specimens determined the landmarks for ultrasonic measurement of knee JSW. The US of 1,272 participants from 27 centers was performed to discuss the feasibility and possible influencing factors of knee JSW. The landmarks for US measurement of knee JS, the inflection point of medial femoral epicondyle and the proximal end of the tibia, were determined. RESULTS: The mean knee JSW1 (medial knee JSW) was 8.57±1.95 mm in females and 9.52±2.31 mm in males. The mean knee JSW2 (the near medial knee JSW) was 9.07±2.24 mm in females and 10.17±2.35 mm in males. The JSW values of males were significantly higher than those of females, with a statistical difference. JSW values were negatively correlated with age and body mass index (BMI) to different degrees and positively correlated with height. CONCLUSIONS: The novel US measurement method can be used to measure knee JSW.

Isotope dilution LC/ESI--MS-MS quantitation of urinary 1,4-bis(N-acetyl-S-cysteinyl)-2-butanone in mice and rats as the biomarker of 1-chloro-2-hydroxy-3-butene, an in vitro metabolite of 1,3-butadiene.

1-Chloro-2-hydroxy-3-butene (CHB) is a possible metabolite of 1,3-butadiene, a carcinogenic air pollutant. To demonstrate its formation in vivo, it is desirable to develop a practical biomarker and the corresponding analysis method. CHB can undergo alcohol dehydrogenase- and cytochromes P450 enzymes (P450)-mediated oxidation to yield 1-chloro-3-buten-2-one (CBO), which readily forms glutathione conjugates. We hypothesized that CBO-derived mercapturic acids, which are the expected biotransformed products of CBO-glutathione conjugates, could be used as CHB biomarkers. Thus, in the present study, we investigated the in vivo biotransformation of CHB into CBO-derived mercapturic acids. Because the reaction of CBO with N-acetyl-l-cysteine yields two products, 1,4-bis(N-acetyl-S-cysteinyl)-2-butanone (NC1) and 1-chloro-4-(N-acetyl-S-cysteinyl)-2-butanone (NC2), we first developed an isotope dilution LC/ESI--MS-MS method to quantitate urinary NC1 and NC2, and then determined their concentrations in urine of C57BL/6 mice and Sprague-Dawley rats administered CHB. Since no NC2 was detected in samples, the LC/ESI--MS-MS method was optimized specifically for NC1. NC1 was enriched through solid phase extraction with the recovery being 75-82%. The limits of detection and quantitation were 6.8 and 34 fmol/0.1 mL for mouse urine, and 4.5 and 7.1 fmol/0.1 mL for rat urine, respectively. In urine of animals before CHB administration, no NC1 was detected; in mice administered CHB at 10 and 30 mg/kg, and rats at 5 and 15 mg/kg, NC1 was detected and its concentrations in urine from animals given higher doses were 3-6 fold higher than those given lower doses. Moreover, the NC1 concentrations in urine during 0-8 h were 4-6 fold and 10-11 fold higher than those during 8-24 h for mice and rats, respectively. The results demonstrated that CHB could be in vivo biotransformed into NC1, which could be used as a practical CHB biomarker.

Molecular Mechanism Regarding Allosteric Modulation of Ligand Binding and the Impact of Mutations on Dimerization for CCR5 Homodimer.

In this work, we combined accelerated molecular dynamics (aMD) and conventional molecular dynamics (cMD) simulations coupled with the potential of mean force (PMF), correlation analysis, principal component analysis (PCA), and protein structure network (PSN) to study the effects of dimerization and the mutations of I52V and V150A on the CCR5 homodimer, in order to elucidate the mechanism regarding cooperativity of the ligand binding between two protomers and to address the controversy about the mutation-induced dimer-separation. The results reveal that the dimer with interface involved in TM1, TM2, TM3, and TM4 is stable for the CCR5 homodimer. The dimerization induces an asymmetric impact on the overall structure and the ligand-binding pocket. As a result, the two protomers exhibit an asymmetric binding to the maraviroc (one anti-HIV drug). The binding of one protomer to the drug is enhanced while the other is weakened. The PSN result further reveals the allosteric pathway of the ligand-binding pocket between the two protomers. Six important residues in the pathway were identified, including two residues unreported. The results from PMF, PCA, and the correlation analysis clearly indicate that the two mutations induce strong anticorrelation motions in the interface, finally leading to its separation. The observations from the work could advance our understanding of the structure of the G protein-coupled receptor dimers and implications for their functions.

Probing the Effects of the Number and Positions of -OCH3 and -CN Substituents on Color Tuning of Ir(III) Complex Derivatives through a Joint Computational and Experimental Study.

We performed a joint theoretical and experimental study on sixteen Ir(III) complexes bearing a similar molecular platform of bis(2-phenylbenzothiozolato-N,C2' ) iridium(III) (acetylacetonate) by grafting -OCH3 group and/or -CN group on different positions of the C-related arene moiety of the C ^ N ligand (C-ring). Our results reveal that the introduction of -CN renders an overall drop in the FMO energy levels while a reverse increase is observed for -OCH3 . The ortho- and para-sites of the C-ring are more effective substitution positions to modulate the HOMO energy level due to the fact that the electronic density of HOMO mainly locates at them while the meta-site would induce a stronger impact on LUMO since the electronic density of LUMO mainly distributes over the position. Utilizing the synergistic effects of the substituents and the substituted positions, a wide color-tuning range from 479 nm to 637 nm was achieved, which covers nearly the whole window of visible spectrum. In particular, the tri-substituted Ir35mo4cn complex (λem max =637 nm) may be a potential candidate for high efficiency red OLEDs materials due to its greatly enhanced absorption processes, relatively higher 3 MLCT (%), lower ΔES1-T1 , enlarged separation between 3 MLCT/π-π* and 3 MC d-d states, and good hole and particle-transporting performances. Finally, six representative complexes were synthesized and their spectra were determined, which confirm the reliability of our computational strategy.