A gelatin methacryloyl (GelMA) treated with gallic acid and coated with specially designed nanoparticles derived from ginseng enhances the healing of wounds in diabetic rats.

Due to persistent inflammation and oxidative stress reactions, achieving drug absorption in diabetic wounds is challenging. To overcome this problem, our article presents a composite hydrogel, GelMA-GA/DMOG@GDNP, which consists of gelatin methacryloyl (GelMA) treated with gallic acid (GA) and encapsulating ginseng-derived nanoparticles (GDNPs) loaded with dimethyloxallyl glycine (DMOG). The composite hydrogel demonstrates excellent biocompatibility. In laboratory settings, the hydrogel inhibits the production of nitric oxide synthase 2 (iNOS) in mouse immune cells (RAW264.7 cells), enhances the growth and migration of mouse connective tissue cells (L929 cells) and human endothelial cells (HUVECs), and promotes tube formation in HUVECs. In a rat model of type 1 diabetes-induced wounds, the composite hydrogel attenuates inflammatory reactions, facilitates the formation of fibres and blood vessels, accelerates wound healing, and elucidates specific pathway mechanisms through transcriptome sequencing. Therefore, the GelMA-GA/DMOG@GDNP hydrogel can serve as a safe and efficient wound dressing to regulate the inflammatory response, promote collagen fiber and blood vessel formation, and accelerate wound healing. These findings suggest that utilizing this multifunctional engineered nanoparticle-loaded hydrogel in a clinical setting may be a promising strategy for diabetic wound healing.

Leaf Senescence Regulation Mechanism Based on Comparative Transcriptome Analysis in Foxtail Millet.

Leaf senescence, a pivotal process in plants, directly influences both crop yield and nutritional quality. Foxtail millet (Setaria italica) is a C4 model crop renowned for its exceptional nutritional value and stress tolerance characteristics. However, there is a lack of research on the identification of senescence-associated genes (SAGs) and the underlying molecular regulatory mechanisms governing this process. In this study, a dark-induced senescence (DIS) experimental system was applied to investigate the extensive physiological and transcriptomic changes in two foxtail millet varieties with different degrees of leaf senescence. The physiological and biochemical indices revealed that the light senescence (LS) variety exhibited a delayed senescence phenotype, whereas the severe senescence (SS) variety exhibited an accelerated senescence phenotype. The most evident differences in gene expression profiles between these two varieties during DIS included photosynthesis, chlorophyll, and lipid metabolism. Comparative transcriptome analysis further revealed a significant up-regulation of genes related to polysaccharide and calcium ion binding, nitrogen utilization, defense response, and malate metabolism in LS. In contrast, the expression of genes associated with redox homeostasis, carbohydrate metabolism, lipid homeostasis, and hormone signaling was significantly altered in SS. Through WGCNA and RT-qPCR analyses, we identified three SAGs that exhibit potential negative regulation towards dark-induced leaf senescence in foxtail millet. This study establishes the foundation for a further comprehensive examination of the regulatory network governing leaf senescence and provides potential genetic resources for manipulating senescence in foxtail millet.

The Role of Cystathionine-ß-Synthase, H2S, and miRNA-377 in Hypoxic-Ischemic Encephalopathy: Insights from Human and Animal Studies.

We aimed to investigate the mechanism underlying the roles of miRNA-377, Cystathionine-ß-synthase (CBS), and hydrogen sulfide (H2S) in the development of hypoxic-ischemic encephalopathy (HIE). We investigated the relationship between CBS, H2S, and miR-377 in both humans with HIE and animals with hypoxic-ischemic insult. An animal model of fetal rats with hypoxic-ischemic brain injury was established, and the fetal rats were randomly assigned to control and hypoxic-ischemic groups for 15 min (mild) and 30 min (moderate) groups. Human samples were collected from children diagnosed with HIE. Healthy or non-neurological disease children were selected as the control group. Hematoxylin-eosin (HE) staining, quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), and western blot were used to conduct this study. Hypoxia-ischemia induced pathological alterations in brain tissue changes were more severe in groups with severe hypoxic insult. miRNA-377 expression levels were upregulated in brain tissue and serum of fetal rats and human samples with HIE compared to controls. Conversely, CBS and H2S expression levels were significantly decreased in both human and animal samples compared to controls. Our findings suggest that CBS is a target gene of miR-377 which may contribute to the development of HIE by regulating CBS/H2S. H2S has a protective effect against hypoxic damage in brain tissue. The study provides new insights into the potential mechanisms underlying the protective role of H2S in hypoxic brain damage and may contribute to the development of novel therapies for HIE.

Early depletion of M1 macrophages retards the progression of glucocorticoid-associated osteonecrosis of the femoral head.

Inflammation stands as a pivotal factor in the pathogenesis of glucocorticoid-associated osteonecrosis of the femoral head (GA-ONFH). However, the vital role played by M1 macrophages, the principal constituents of the inflammatory process, remains largely underexplored. In this study, we employed reverse transcription-quantitative polymerase chain Reaction (RT-PCR), western blot, and flow cytometry to assess the impact of M1-conditioned medium on cultures of mouse bone marrow-derived mesenchymal stem cells (BMSCs) and Murine Long bone Osteocyte-Y4 (MLO-Y4) in vitro. Moreover, we quantified the levels of inflammatory cytokines in the M1-conditioned medium through the employment of an enzyme-linked immunosorbent assay (ELISA). For in vivo analysis, we examined M1 macrophages and investigated the NF-kB signaling pathway in specimens obtained from the femoral heads of animals and humans. We found that the number of M1 macrophages in the femoral head of GA-ONFH patients grew significantly, and in the mice remarkably increase, maintaining high levels in the intramedullary. In vitro, the M1 macrophage-conditioned medium elicited apoptosis in BMSCs and MLO-Y4 cells, shedding light on the intricate interplay between macrophages and these cell types. The presence of TNF-α within the M1-conditioned medium activated the NF-κB pathway, providing mechanistic insight into the apoptotic induction. Moreover, employing a robust rat macrophage clearance model and GA-ONFH model, we demonstrated a remarkable attenuation in TNF-α expression and NF-kB signaling subsequent to macrophage clearance. This pronounced reduction engenders diminished cellular apoptosis and engenders a decelerated trajectory of GA-ONFH progression. In conclusion, our study reveals the crucial involvement of M1 macrophages in the pathogenesis of GA-ONFH, highlighting their indispensable role in disease progression. Furthermore, early clearance emerges as a promising strategy for impeding the development of GA-ONFH.

Circular RNA circ_0020014 contributes to osteoarthritis progression via miR-613/ADAMTS5 axis.

Circular RNAs (circRNAs) have been shown to be significant regulators in osteoarthritis (OA), whereas the functional effect of circ_0020014 in OA remains unclear. Our goal was to try and understand the underlying regulatory mechanism of circ_0020014 in OA. The cartilage tissue was obtained from OA patients and trauma patients. Interleukin-1ß (IL-1ß)-treated chondrocytes (CHON-001) were used as the in vitro cellular model for OA. The expression levels of circ_0020014, microRNA-613 (miR-613), and a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5) were examined by real-time quantitative polymerase chain reaction (RT-qPCR). The protein level was detected using the western blot assay. Cell viability and apoptosis were measured by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazol-3-ium bromide (MTT) and flow cytometry assays, respectively. The secretion of inflammatory cytokine was determined by enzyme-linked immunosorbent assay (ELISA). Circ_0020014 was upregulated in OA cartilage tissues and IL-1ß-treated CHON-001 cells, compared with that in healthy cartilage tissues and untreated cells. IL-1ß treatment induced cell injury by promoting inflammation and apoptosis, and inhibiting cell viability and extracellular matrix (ECM) accumulation in chondrocytes. Circ_0020014 knockdown significantly protected CHON-001 cells from IL-1ß-induced cell dysfunction. MiR-613 was targeted by circ_0020014 and negatively regulated ADAMTS5 expression. In addition, miR-613 downregulation or ADAMTS5 overexpression partly lessened the protective effect of circ_0020014 knockdown on IL-1ß-treated CHON-001 cells. Collectively, circ_0020014 acted as a miR-613 sponge to regulate ADAMTS5 expression, thereby protecting chondrocytes from IL-1ß-induced inflammatory damage, which might be a novel diagnostic marker for OA.

Experimental Study on the Correlation between miRNA-373 and HIF-1α, MMP-9, and VEGF in the Development of HIE.

INTRODUCTION: Microribonucleic acids (miRNAs) have short (approximately 18 to 25) nucleotides and are evolutionarily conserved and endogenously expressed RNAs belonging to a family of noncoding RNA molecules. miRNA-373 regulates cell proliferation, migration, apoptosis, invasion, and repairing damaged DNA after hypoxia stress. Neonatal hypoxic-ischemic encephalopathy (HIE) refers to perinatal asphyxia caused by partial or complete hypoxia, reduced or suspended cerebral blood flow, and fetal or neonatal brain damage. We aim to investigate the relationship between miRNA-373 and HIF-1α, between miRNA-373 MMP-9, and between miRNA-373 VEGF in the occurrence and development of HIE. METHODS: Human (children) samples were divided into four groups (n = 15 in each group) according to HIE severity. The patient group was divided into middle, moderate, and severe HIE groups. The control group included healthy children or children with nonneurological diseases. The expressions of miRNA-373, HIF-1α, MMP-9, and VEGF were assayed in the serum samples. RESULTS: Our study showed a strong relationship between miRNA-373 and HIF-1α, between miRNA-373 and MMP-9, and between miRNA-373 and VEGF. The expression levels of miRNA-373, HIF-1α, MMP-9, and VEGF in the HIE groups were much higher than those of the control group. CONCLUSION: The increased change in miRNA-373 expression has a certain diagnostic significance on neonatal HIE. In the occurrence and development of HIE, miRNA-373 is positively correlated with HIF-1α, MMP-9, and VEGF.

Overexpression of HIPK2 removes the transrepression of proapoptotic genes mediated by the CtBP1-p300-FOXO3a complex and increases the chemosensitivity in osteosarcoma cells.

Decreased expression of proapoptotic genes can lead to the chemoresistenance in cancer therapy. Carboxyl-terminal binding protein 1 (CtBP1), a transcriptional corepressor with multiple oncogenic effects, has been previously identified to suppress the expression of two proapoptotic genes [BAX (BCL2 associated X) and BIM (Bcl-2 interacting mediator of cell death)] by assembling a complex with the Forkhead box O3 (FOXO3a) transcription factor and the p300 histone acetyltransferase. However, the upstream regulatory signaling of the CtBP1-p300-FOXO3a complex is obscure, and the effects of changing this signaling on chemosensitivity in osteosarcoma are unknown. Herein, we discovered that the downregulation of HIPK2 (Homeodomain-interacting protein kinase 2) was essential for the function of the CtBP1-p300-FOXO3a complex. Downregulation of HIPK2 prevented the phosphorylation and subsequent degradation of CtBP1, thereby allowing the assembly of the CtBP1-p300-FOXO3a complex and suppression of the expression of proapoptotic genes, such as BAX, BIM, BIK (Bcl-2 interacting killer) and NOXA/PMAIP1 (Phorbol-12-myristate-13-acetate-induced protein 1). Overexpression of HIPK2 promoted the phosphorylation of CtBP1 and the degradation of CtBP1 by proteasomes, thereby preventing the formation of the CtBP1-p300-FOXO3a complex. The abolition of CtBP1 transrepression increased the expression of proapoptotic genes to induce apoptosis and increase chemosensitivity in osteosarcoma cells. Taken together, our in vitro and in vivo results revealed that overexpression of HIPK2 could remove the CtBP1-mediated transrepression of proapoptotic genes, indicating a new therapeutic option for the treatment of osteosarcoma.

Targeting the CtBP1-FOXM1 transcriptional complex with small molecules to overcome MDR1-mediated chemoresistance in osteosarcoma cancer stem cells.

Chemoresistance is a major barrier for the chemotherapy of osteosarcoma. The induction of multidrug resistance protein 1 (MDR1), an ATP-dependent transporter, can efflux anti-cancer drugs, thereby decreasing chemosensitivity. However, an actual involvement of MDR1 in the chemoresistance of osteosarcoma cells has not been established. We obtained two cisplatin (CDDP)-resistant osteosarcoma cancer stem cell (CSC) lines using sphere formation medium supplemented with CDDP. These two CDDP-resistant CSC cell lines showed substantial cell proliferation, colony formation, cell invasion, and in vivo tumor growth in the presence of CDDP. Microarray analysis revealed that three genes, MDR1, FOXM1 (forkhead box M1), and CtBP1 (C-Terminal binding protein 1), showed significant overexpression in both cell lines. Mechanistically, CtBP1 assembled with FOXM1 to form a transcriptional complex, which docked onto the MDR1 promoter to activate MDR1 expression. Knockdown or inhibition of the CtBP1-FOXM1 components with specific small molecules, including NSM00158 and NSC95397 for CtBP1 and RCM1 for FOXM1, significantly repressed MDR1 expression. Administration of these three small molecules also significantly inhibited tumor growth in mouse tumor xenograft model. The MDR1-mediated chemoresistance could be reversed by NSM00158 and RCM1. Collectively, our data revealed that the CtBP1-FOXM1 complex activated MDR1 expression and that targeting this complex with their specific inhibitors could reverse MDR1-mediated chemoresistance both in vitro and in vivo. Our results indicate a new therapeutic strategy for overcoming chemoresistance during osteosarcoma treatment.

Circ_DHRS3 positively regulates GREM1 expression by competitively targeting miR-183-5p to modulate IL-1ß-administered chondrocyte proliferation, apoptosis and ECM degradation.

BACKGROUND: Osteoarthritis (OA) is a chronic inflammatory disease caused by degenerative changes of articular cartilage, involving in the expression changes of special circular RNAs (circRNAs). This study aimed to explore the role of circ_DHRS3 in OA cell models and provide a potential mechanism. METHODS: OA cell models were constructed using human chondrocytes with Interleukin-1 beta (IL-1ß) treatment. The expression of circ_DHRS3, microRNA (miR)-183-5p and Gremlin 1 (GREM1) mRNA was detected using real-time quantitative polymerase chain reaction (RT-qPCR). Cell proliferation was identified using 3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyl tetrazolium bromide (MTT) assay. Cell apoptosis was investigated using flow cytometry assay. The protein levels of proliferation- and apoptosis-related proteins were quantified by western blot. The levels of extracellular matrix (ECM)-associated proteins were quantified by western blot to assess ECM degradation. The relationship between miR-183-5p and circ_DHRS3 or GREM1 was predicted and then verified by dual-luciferase reporter assay. RESULTS: Circ_DHRS3 expression was elevated in OA cartilage tissues and IL-1ß-treated chondrocytes. Circ_DHRS3 was resistant to RNase R and Actinomycin D. Circ_DHRS3 knockdown promoted chondrocyte proliferation inhibited by IL-1ß, and alleviated IL-1ß-induced apoptosis and ECM degradation, which were reversed by the inhibition of miR-183-5p, a target of circ_DHRS3. MiR-183-5p restoration also enhanced IL-1ß-blocked cell proliferation, and relieved IL-1ß-induced cell apoptosis and ECM degradation, while GREM1 (a target of miR-183-5p) overexpression abolished the effects of miR-183-5p restoration. Moreover, circ_DHRS3 regulated GREM1 expression by targeting miR-183-5p. CONCLUSION: Circ_DHRS3 mediated IL-1ß-administered chondrocyte proliferation, apoptosis and ECM degradation by positively regulating GREM1 expression via competitively targeting miR-183-5p.

NSM00158 Specifically Disrupts the CtBP2-p300 Interaction to Reverse CtBP2-Mediated Transrepression and Prevent the Occurrence of Nonunion.

Carboxyl-terminal binding proteins (CtBPs) are transcription regulators that control gene expression in multiple cellular processes. Our recent findings indicated that overexpression of CtBP2 caused the repression of multiple bone development and differentiation genes, resulting in atrophic nonunion. Therefore, disrupting the CtBP2-associated transcriptional complex with small molecules may be an effective strategy to prevent nonunion. In the present study, we developed an in vitro screening system in yeast cells to identify small molecules capable of disrupting the CtBP2-p300 interaction. Herein, we focus our studies on revealing the in vitro and in vivo effects of a small molecule NSM00158, which showed the strongest inhibition of the CtBP2-p300 interaction in vitro. Our results indicated that NSM00158 could specifically disrupt CtBP2 function and cause the disassociation of the CtBP2-p300-Runx2 complex. The impairment of this complex led to failed binding of Runx2 to its downstream targets, causing their upregulation. Using a mouse fracture model, we evaluated the in vivo effect of NSM00158 on preventing nonunion. Consistent with the in vitro results, the NSM00158 treatment resulted in the upregulation of Runx2 downstream targets. Importantly, we found that the administration of NSM00158 could prevent the occurrence of nonunion. Our results suggest that NSM00158 represents a new potential compound to prevent the occurrence of nonunion by disrupting CtBP2 function and impairing the assembly of the CtBP2-p300-Runx2 transcriptional complex.

[Application of bone transport with unilateral external fixator combined with locked plate internal fixation in treatment of infected tibial nonunion].

Objective: To summarize the effectiveness of bone transport with unilateral external fixator combined with locked plate internal fixation in treatment of infected tibial nonunion. Methods: Between January 2010 and December 2014, 23 patients with infected tibial nonunion were treated with bone transport with unilateral external fixator combined with locked plate internal fixation. There were 19 males and 4 females with an average age of 37.8 years (range, 19-54 years). The mean length of the bone defect was 6.5 cm (range, 5.2-8.1 cm). The number of previous operations ranged from 2 to 4 times, with an average of 2.5 times. The time from injury to this treatment was 7-23 months, with an average of 11.8 months. The time of bone transport, time of the external fixation, fracture healing time, external fixation index, healing index, and complication were recorded; and the Association for the Study and Application of the Methods of Ilizarov (ASAMI) bone healing and function scores were used to evaluate the effectiveness. Results: All patients were followed up 3-6 years with an average of 4.8 years. Wounds and bone defects healed in all patients. No complication such as infection recurrence, nonunion, re-fracture, malunion, iatrogenic nerve paralysis, or stiffness of knee and ankle joints occurred. Five patients had needle infections which were treated by local care and no deep infection occurred. The time of bone transport was 65-120 days (mean, 75.6 days); the time of the external fixation was 75-145 days (mean, 97.8 days); the fracture healing time was 4-17 months (mean, 8.7 months); the external fixation index was 18-28 days/cm (mean, 22.4 days/cm); and the healing index was 31-52 days/cm (mean, 40.2 days/cm). At last follow-up, according to ASAMI criteria, the result of bone healing was excellent in 15 cases and good in 8 cases, and the result of function was excellent in 18 cases and good in 5 cases, all with the excellent and good rate of 100%. Conclusion: For infected tibial nonunion, bone transport with unilateral external fixator combined with locked plate internal fixation can reduce the time of external fixation and related complications, with a satisfactory effectiveness.

[New progress on three-dimensional movement measurement analysis of human spine].

Spinal biomechanics, especially the range of spine motion,has close connection with spinal surgery. The change of the range of motion (ROM) is an important indicator of diseases and injuries of spine, and the essential evaluating standards of effect of surgeries and therapies to spine. The analysis of ROM can be dated to the time of the invention of X-ray and even that before it. With the development of science and technology as well as the optimization of various types of calculation methods, diverse measuring methods have emerged, from imaging methods to non-imaging methods, from two-dimensional to three-dimensional, from measuring directly on the X-ray films to calculating automatically by computer. Analysis of ROM has made great progress, but there are some older methods cannot meet the needs of the times and disappear, some classical methods such as X-ray still have vitality. Combining different methods, three dimensions and more vivo spine research are the trend of analysis of ROM. And more and more researchers began to focus on vivo spine research. In this paper, the advantages and disadvantages of the methods utilized recently are presented through viewing recent literatures, providing reference and help for the movement analysis of spine.

Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 1. Adsorption capacity and kinetics.

The adsorption of two representative PhACs (naproxen and carbamazepine) and one EDC (nonylphenol) were evaluated on two granular activated carbons (GAC). The primary objective was to investigate preloading effects by natural organic matter (NOM) on adsorption capacity and kinetics under conditions and concentrations (i.e., ng/L) relevantfor drinking water treatment Isotherms demonstrated that all compounds were significantly negatively impacted by NOM fouling. Adsorption capacity reduction was most severe for the acidic naproxen, followed by the neutral carbamazepine and then the more hydrophobic nonylphenol. The GAC with the wider pore size distribution had considerably greater NOM loading, resulting in lower adsorption capacity. Different patterns forthe change in Freundlich K(F) and 1/n with time revealed different competitive mechanisms for the different compounds. Mass transport coefficients determined by short fixed-bed (SFB) tests with virgin and preloaded GAC demonstrated thatfilm diffusion primarily controls mass transfer on virgin and preloaded carbon. Naproxen suffered the greatest deteriorative effect on kinetic parameters due to preloading, followed by carbamazepine, and then nonylphenol. A type of surface NOM/biofilm, which appeared to add an additional masstransfer resistance layer and thus reduce film diffusion, was observed. In addition, electrostatic interactions between NOM/biofilm and the investigated compounds are proposed to contribute to the reduction of film diffusion. A companion paper building on this work describes treatability studies in pilot-scale GAC adsorbers and the effectiveness of a selected fixed-bed model.

Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 2. Model prediction.

The adsorption of two representative pharmaceutically active compounds (PhACs)-naproxen and carbamazepine and one endocrine disrupting compound (EDC)-nonylphenol was studied in pilot-scale granular activated carbon (GAC) adsorbers using post-sedimentation (PS) water from a full-scale drinking water treatment plant. Acidic naproxen broke through fastest while nonylphenol was removed best, which was consistent with the degree to which fouling affected compound removals. Model predictions and experimental data were generally in good agreement for all three compounds, which demonstrated the effectiveness and robustness of the pore and surface diffusion model (PSDM) used in combination with the time-variable parameter approach for predicting removals at environmentally relevant concentrations (i.e., ng/L range). Sensitivity analyses suggested that accurate determination of film diffusion coefficients was critical for predicting breakthrough for naproxen and carbamazepine, in particular when high removals are targeted. Model simulations demonstrated that GAC carbon usage rates (CURs) for naproxen were substantially influenced by the empty bed contact time (EBCT) at the investigated conditions. Model-based comparisons between GAC CURs and minimum CURs for powdered activated carbon (PAC) applications suggested that PAC would be most appropriate for achieving 90% removal of naproxen, whereas GAC would be more suitable for nonylphenol.

Adsorption characteristics of selected pharmaceuticals and an endocrine disrupting compound-Naproxen, carbamazepine and nonylphenol-on activated carbon.

The adsorption of two representative pharmaceutically active compounds (PhACs) (naproxen and carbamazepine) and one endocrine disrupting compound (nonylphenol) were evaluated on two types of activated carbon. When determining their isotherms at environmentally relevant concentration levels, it was found that at this low concentration range (10-800 ng/L), removals of the target compounds were contrary to expectations based on their hydrophobicity. Nonylphenol (log K(ow) 5.8) was most poorly adsorbed, whereas carbamazepine (log K(ow) 2.45) was most adsorbable. Nonylphenol Freundlich isotherms at this very low concentration range had a much higher 1/n compared to isotherms at much higher concentrations. This indicates that extrapolation from an isotherm obtained at a high concentration range to predict the adsorption of nonylphenol at a concentration well below the range of the original isotherm, leads to a substantial overestimation of its removals. Comparison of isotherms for the target compounds to those for other conventional micropollutants suggested that naproxen and carbamazepine could be effectively removed by applying the same dosage utilized to remove odorous compounds (geosmin and MIB) at very low concentrations. The impact of competitive adsorption by background natural organic matter (NOM) on the adsorption of the target compounds was quantified by using the ideal adsorbed solution theory (IAST) in combination with the equivalent background compound (EBC) approach. The fulfilment of the requirements for applying the simplified IAST-EBC model, which leads to the conclusion that the percentage removal of the target compounds at a given carbon dosage is independent of the initial contaminant concentration, was confirmed for the situation examined in the paper. On this basis it is suggested that the estimated minimum carbon usage rates (CURs) to achieve 90% removal of these emerging contaminants would be valid at concentrations of less than 500 ng/L in natural water.

Optimizing gas chromatographic-mass spectrometric analysis of selected pharmaceuticals and endocrine-disrupting substances in water using factorial experimental design.

An analytical method based on gas chromatography-mass spectrometry (GC-MS) has been developed to simultaneously determine selected acidic and neutral pharmaceuticals and endocrine-disrupting substances in surface and tap water. Solid-phase extraction (SPE) with Oasis HLB cartridges is followed by derivatization of the target analytes in the eluted extract. Derivatization was systematically optimized by employing a factorial experimental design. More specifically a central composite design was applied to search for the optimal conditions of the derivatization process and it was demonstrated that N-methyl-N-tert-butyl-dimethysilyl-trifluoroacetamide (MTBSTFA) had a better overall performance compared to N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA). The influence of solvent ratios and elution volumes while using SPE were also studied using a factorial design. The method was developed successfully for most of the selected compounds [i.e. ibuprofen, salicylic acid, gemfibrozil, naproxen, triclosan, propranolol, diclofenac, carbamazepine, 4-octylphenol (OP), 4-nonylphenol (NP), nonylphenol-monoethoxylate (NP1EO), nonylphenoxyacetic acid (NP1EC), estrone (E1), and 17alpha-ethinyloestradiol (EE2)]. Relative recoveries for spiked river and tap water ranged from 47 to 130% and 60-109%, respectively. Typical limits of detection were less than 5 ng/L in tap water and less than 10 ng/L in river water. Twelve target compounds were detected in river and tap water samples using the developed method. This method is currently used in bench-scale drinking water treatment studies.

The interference of 2-chloro-5-oxo-3-hexene diacyl chloride (COHC) in the detection of strong mutagen MX.

The MX formation potential of some compounds belong to benzoic acids, benzoic aldehydes and phenols families was investigated. Only some structures with aldehyde group can form MX, which is inconsistent with other research. A new compound 2-chloro-5-oxo-3-hexene diacyl chloride (COHC) was found. It will seriously interfere with the detection of MX when the GC/MS instrument is operated in select ion monitoring mode because its retention time is very close to that of methylated MX and it has a set of characteristic ions m/z 199, 201, 203, which is widely used in the detection of MX. The detection of COHC has not been reported previously. However, according to its formation mechanism it will widely occur in chlorinated drinking and humic water. Due to the presence of COHC, some of the former research results on MX should be revised.

[Detection of the strong mutagen MX in drinking water].

MX [3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone] was found to be the most potent mutagen in chlorinated drinking water. MX in some tap waters in Jiangsu Province was absorbed by XAD-8 resin, methylized with saturated BF3-CH3OH and detected using GC/MS. The contents of MX in the tap waters were between 0.58 to 20.0 ng.L-1, except one of those samples. More MX was produced in low-water season.