Discovery of toxoflavin, a potent IRE1α inhibitor acting through structure-dependent oxidative inhibition.

Inositol-requiring enzyme 1α (IRE1α) is the most conserved endoplasmic reticulum (ER) stress sensor with two catalytic domains, kinase and RNase, in its cytosolic portion. IRE1α inhibitors have been used to improve existing clinical treatments against various cancers. In this study we identified toxoflavin (TXF) as a new-type potent small molecule IRE1α inhibitor. We used luciferase reporter systems to screen compounds that inhibited the IRE1α-XBP1s signaling pathway. As a result, TXF was found to be the most potent IRE1α RNase inhibitor with an IC50 value of 0.226 µM. Its inhibitory potencies on IRE1α kinase and RNase were confirmed in a series of cellular and in vitro biochemical assays. Kinetic analysis showed that TXF caused time- and reducing reagent-dependent irreversible inhibition on IRE1α, implying that ROS might participate in the inhibition process. ROS scavengers decreased the inhibition of IRE1α by TXF, confirming that ROS mediated the inhibition process. Mass spectrometry analysis revealed that the thiol groups of four conserved cysteine residues (CYS-605, CYS-630, CYS-715 and CYS-951) in IRE1α were oxidized to sulfonic groups by ROS. In molecular docking experiments we affirmed the binding of TXF with IRE1α, and predicted its binding site, suggesting that the structure of TXF itself participates in the inhibition of IRE1α. Interestingly, CYS-951 was just near the docked site. In addition, the RNase IC50 and ROS production in vitro induced by TXF and its derivatives were negative correlated (r = -0.872). In conclusion, this study discovers a new type of IRE1α inhibitor that targets a predicted new alternative site located in the junction between RNase domain and kinase domain, and oxidizes conserved cysteine residues of IRE1α active sites to inhibit IRE1α. TXF could be used as a small molecule tool to study IRE1α's role in ER stress.

Dual Photo-Responsive Diphenylacetylene Enables PET In-Situ Upcycling with Reverse Enhanced UV-Resistance and Strength.

A novel in situ chemical upcycling strategy for plastic waste is proposed by the customized diphenylacetylene monomer with dual photo-response. That is, diphenylacetylene reactive monomers are in situ inserted into the macromolecular chain of polyethylene terephthalate (PET) plastics/fibers through one-pot transesterification of slight-depolymerization and re-polymerization. On the one hand, the diphenylacetylene group absorbs short-wave high-energy UV rays and then releases long-wave low-energy harmless fluorescence. On the other hand, the UV-induced photo-crosslinking reaction among diphenylacetylene groups produces extended π-conjugated structure, resulting in a red-shift (due to decreased HOMO-LUMO separation) in the UV absorption band and locked crosslink points between PET chains. Therefore, with increasing UV exposure time, the upcycled PET plastics exhibit reverse enhanced UV resistance and mechanical strength (superior to original performance), instead of serious UV-photodegradation and damaged performance. This upcycling strategy at oligomer-scale not only provides a new idea for traditional plastic recycling, but also solves the common problem of gradual degradation of polymer performance during use.

Connexin32 activates necroptosis through Src-mediated inhibition of caspase 8 in hepatocellular carcinoma.

Necroptosis is an alternative form of programmed cell death that generally occurs under apoptosis-deficient conditions. Our previous work showed that connexin32 (Cx32) promotes the malignant progress of hepatocellular carcinoma (HCC) by enhancing the ability of resisting apoptosis in vivo and in vitro. Whether triggering necroptosis is a promising strategy to eliminate the apoptosis-resistant HCC cells with high Cx32 expression remains unknown. In this study, we found that Cx32 expression was positively correlated with the expression of necroptosis protein biomarkers in human HCC specimens, cell lines, and a xenograft model. Treatment with shikonin, a well-used necroptosis inducer, markedly caused necroptosis in HCC cells. Interestingly, overexpressed Cx32 exacerbated shikonin-induced necroptosis, but downregulation of Cx32 alleviated necroptosis in vitro and in vivo. Mechanistically, Cx32 was found to bind to Src and promote Src-mediated caspase 8 phosphorylation and inactivation, which ultimately reduced the activated caspase 8-mediated proteolysis of receptor-interacting serine-threonine protein kinase 1/3, the key molecule for necroptosis activation. In conclusion, we showed that Cx32 contributed to the activation of necroptosis in HCC cells through binding to Src and then mediating the inactivation of caspase 8. The present study suggested that necroptosis inducers could be more favorable than apoptosis inducers to eliminate HCC cells with high expression of Cx32.

Azoxystrobin, a mitochondrial complex III Qo site inhibitor, exerts beneficial metabolic effects in vivo and in vitro.

BACKGROUND: Several anti-diabetes drugs exert beneficial effects against metabolic syndrome by inhibiting mitochondrial function. Although much progress has been made toward understanding the role of mitochondrial function inhibitors in treating metabolic diseases, the potential effects of these inhibitors on mitochondrial respiratory chain complex III remain unclear. METHODS: We investigated the metabolic effects of azoxystrobin (AZOX), a Qo inhibitor of complex III, in a high-fat diet-fed mouse model with insulin resistance in order to elucidate the mechanism by which AZOX improves glucose and lipid metabolism at the metabolic cellular level. RESULTS: Acute administration of AZOX in mice increased the respiratory exchange ratio. Chronic treatment with AZOX reduced body weight and significantly improved glucose tolerance and insulin sensitivity in high-fat diet-fed mice. AZOX treatment resulted in decreased triacylglycerol accumulation and down-regulated the expression of genes involved in liver lipogenesis. AZOX increased glucose uptake in L6 myotubes and 3T3-L1 adipocytes and inhibited de novo lipogenesis in HepG2 cells. The findings indicate that AZOX-mediated alterations to lipid and glucose metabolism may depend on AMP-activated protein kinase (AMPK) signaling. CONCLUSIONS: AZOX, a Qo inhibitor of mitochondrial respiratory complex III, exerts whole-body beneficial effects on the regulation of glucose and lipid homeostasis in high-fat diet-fed mice. GENERAL SIGNIFICANCE: These findings provide evidence that a Qo inhibitor of mitochondrial respiratory complex III could represent a novel approach for the treatment of obesity.

Synthesis of one-dimensional Schiff base polymers that contain an oligothiophene building block on the graphite surface.

Surface-mediated Schiff base coupling reactions between oligothiophenes equipped with an aldehyde group and aromatic diamines were investigated on highly oriented pyrolytic graphite (HOPG) by means of scanning tunneling microscopy (STM) under ambient conditions. To investigate the evolution process from monomers to resultant polymers and the mechanism of reactions, we controlled the ratio of precursors and the reactive temperature, and we obtained high-resolution STM images of different stages of the surface reaction. The results suggest that preferential adsorption of one kind of monomer has a great influence on the on-surface Schiff base reaction.

Berberine combined with 2-deoxy-d-glucose synergistically enhances cancer cell proliferation inhibition via energy depletion and unfolded protein response disruption.

BACKGROUND: Targeting multiple aspects of cellular metabolism, such as both aerobic glycolysis and mitochondrial oxidative phosphorylation (OXPHOS), has the potential to improve cancer therapeutics. Berberine (BBR), a widely used traditional Chinese medicine, exerts its antitumor effects by inhibiting OXPHOS. 2-Deoxy-d-glucose (2-DG) targets aerobic glycolysis and demonstrates potential anticancer effects in the clinic. We hypothesized that BBR in combination with 2-DG would be more efficient than either agent alone against cancer cell growth. METHODS: The effects of BBR and 2-DG on cancer cell growth were evaluated using the Sulforhodamine B (SRB) method. Cell death was detected with the PI uptake assay, and Western blot, Q-PCR and luciferase reporter assays were used for signaling pathway detection. An adenovirus system was used for gene overexpression. RESULTS: BBR combined with 2-DG synergistically enhanced the growth inhibition of cancer cells in vitro. Further mechanistic studies showed that the combination drastically enhanced ATP depletion and strongly disrupted the unfolded protein response (UPR). Overexpressing GRP78 partially prevented the cancer cell inhibition induced by both compounds. CONCLUSIONS: Here, we report for the first time that BBR and 2-DG have a synergistic effect on cancer cell growth inhibition related to ATP energy depletion and disruption of UPR. GENERAL SIGNIFICANCE: Our results propose the potential use of BBR and 2-DG in combination as an anticancer treatment, reinforcing the hypothesis that targeting both aerobic glycolysis and OXPHOS provides more effective cancer therapy and highlighting the important role of UPR in the process.

5-Sulfanyl-idene-2H,5H-1,3-dithiolo[4,5-d][1,3]dithiol-2-one.

The title mol-ecule, C(4)OS(5), is essentially planar, with an r.m.s. deviation of 0.032 (3) Å. All the C-S single bonds are shorter than the standard Csp(3)-S single-bond length, showing the π-conjugated nature of the molecule. In the crystal, molecules lie parallel to one another and pack in columns along the a axis. Short inter-molecular S⋯S contacts [3.314 (3), 3.482 (2) and 3.501 (2) Å] are observed between the columns. The angle between the two mol-ecular dipole moments in the unit cell is 39.3 (1)° and the macro-polarization vector is along the [1 0 - 1.41] direction. As a result of the high polarization and π-conjugation of the structure, the crystalline powder exhibits a second harmonic generating intensity, which is as strong as that of the urea standard powder crystals, when irradiated by a 1053 nm laser beam. The diffraction space of the crystal showed a nonmerohedral twinning.

Cx32 promotes autophagy and produces resistance to SN­induced apoptosis via activation of AMPK signalling in cervical cancer.

The roles of gap junctions (GJs) and its components, connexins, in the autophagy of cervical cancer cells have been rarely investigated. Our previous study demonstrated that connexin 32 (Cx32) exerted an anti­apoptotic effect on cervical cancer. However, as an important regulator of apoptosis, whether the autophagy is involved in the function of Cx32 on cervical cancer cells is not well defined. The present study aimed to investigate the role of Cx32 on autophagy and apoptosis inhibition in cervical cancer cells. The expression levels of Cx32 and the autophagy­associated protein LC3­â…¡ in paracancerous cervical tissues (n=30) and cervical cancer (n=50) tissues were determined via western blotting. In total, 45 cervical cancer specimens were used to evaluate the clinical relevance of Cx32 and LC3­â…¡. It was found that both Cx32 and LC3­â…¡ were upregulated in cervical cancer tissues compared with those in paracancerous cervical tissues. The effect of Cx32 on autophagy was examined by detecting the change of LC3­â…¡ using western blotting, transfection with enhanced green fluorescent protein­LC3 plasmid and transmission electron microscopy analysis. Overexpression of Cx32 significantly enhanced autophagy in HeLa­Cx32 cells, whereas knockdown of Cx32 suppressed autophagy in C­33A cells. The flow cytometry results demonstrated that Cx32 inhibited the apoptosis of cervical cancer cells by promoting autophagy. Moreover, Cx32 triggered autophagy via the activation of the AMP­activated protein kinase (AMPK) signalling, regardless of the presence or absence of GJs. Collectively, it was identified that Cx32 exerted its anti­apoptotic effect by activating autophagy via the AMPK pathway in cervical cancer, which demonstrates a novel mechanism for Cx32 in human cervical cancer progression.

[Research Advances on the Senescence Mechanism of Bone Marrow Mesenchymal Stem Cells Derived from Patients with Myelodysplastic Syndrome--Review].

Emerging data have demonstrated that bone marrow mesenchymal stem cells (MSCs) play important roles in the progression of myelodysplastic syndrome (MDS). Experiments in vitro have showed that MSCs derived from MDS patients (MDS-MSC) exhibit the biological characteristics of cell senescence. Although the underlying mechanisms that regulate cell senescence need to be further elucidated, existing researches indicate that the mechanisms of MDS-MSC senescence have significant heterogeneity. Depth understanding of the underlying mechanisms involved in cell senescence of MDS-MSC are crucial to explore the potential therapeutic target of MDS. Therefore, this review summarizes research advances related with MSC senescence, such as MDS-MSC intrinsic changes in telomere shortening, DNA methylation status, oxidative stress and signal pathways regulating cell senescence in recent years.

Two novel diterpenes from the stems and leaves of tropical seagrass Enhalus acoroides in the South China sea.

Two novel diterpenes Enhoidin A (1) and Enhoidin B (2) featuring an unusual gibberellane skeleton were isolated from the stems and leaves of Enhalus acoroides. Their structures were elucidated on the basis of spectroscopic analysis including 1D and 2D NMR techniques and HR-ESI-MS. This is the first time that this type of lactone ring between C-18 and C-20 has been found among gibberellanes from the tropical seagrasses. Evaluation of the all compounds for cytotoxicity against four human cancer cell lines (MCF-7, HCT-116, HepG-2 and HeLa), and showed moderate cytotoxic activities.

[Analysis of Proliferation Characters of Bone Marrow Mesenchymal Stem Cells Derived from Patients with Myelodysplastic Syndrome].

OBJECTIVE: To analyze the proliferation potential of bone marrow-derived mesenchymal stem cells (MSC) in patients with myelodysplastic syndrome (MDS). METHODS: The MSC derived from the 24 patients with newly diagnosed MDS (MDS-MSC group) and MSC derived from 15 patients with nutritional anemia (control group) in the Affiliated Hospital of Hebei University were used as the research objects. The proliferation potential of MSC was analyzed by colony-forming unit assay, doubling time, cumulative passaging, cell number after 10 days of culture with equal amount of MSC and MTT experiment. The mechanism of abnormal proliferation was analyzed by cell cycle experiment, apoptosis experiment and p21 gene expression assay. RESULTS: In the colony forming unit assay, the number of MDS-MSC colonies was 4.44±2.51, which was significantly lower than that of the control group (12.44±2.55)(P<0.01); the doubling time of MDS-MSC group was significantly longer than that of the control group (7.80±3.26 vs 3.63±0.85) (P<0.01); the number of MDS-MSC in 5×104 culture for 10 days was (39.40±14.18)×104, which was significantly lower than that of the control group ï¼»(85.30±9.49)×104 ï¼½(P<0.01); the number of cumulative passages in MDS-MSC group was 5.20±1.40, which was significantly lower than that in control group (11.60±1.96)(P<0.01); MTT results showed that the proliferation capability of MSC in MDS-MSC group was lower than that in the control group. The cell proportion of G0/G1 phase in MDS-MSC group was higher than that in the control group, while the cell proportion of S phase was lower (P<0.05). The percentage of early apoptotic cells in MDS-MSC group was higher than that in control group (P<0.05); the relative expression level of p21 mRNA in MDS-MSC group was significantly higher than that in control group(P<0.01). CONCLUSION: The proliferative capability of MDS-MSC is significantly reduced, which relates with the arrest of cell cycle in G0/G1 phase, the increase of early apoptotic cells and senescent cells of the MDS-MSC.

Transcriptome integration analysis and specific diagnosis model construction for Hodgkin's lymphoma, diffuse large B-cell lymphoma, and mantle cell lymphoma.

Transcriptome differences between Hodgkin's lymphoma (HL), diffuse large B-cell lymphoma (DLBCL), and mantle cell lymphoma (MCL), which are all derived from B cell, remained unclear. This study aimed to construct lymphoma-specific diagnostic models by screening lymphoma marker genes. Transcriptome data of HL, DLBCL, and MCL were obtained from public databases. Lymphoma marker genes were screened by comparing cases and controls as well as the intergroup differences among lymphomas. A total of 9 HL marker genes, 7 DLBCL marker genes, and 4 MCL marker genes were screened in this study. Most HL marker genes were upregulated, whereas DLBCL and MCL marker genes were downregulated compared to controls. The optimal HL-specific diagnostic model contains one marker gene (MYH2) with an AUC of 0.901. The optimal DLBCL-specific diagnostic model contains 7 marker genes (LIPF, CCDC144B, PRO2964, PHF1, SFTPA2, NTS, and HP) with an AUC of 0.951. The optimal MCL-specific diagnostic model contains 3 marker genes (IGLV3-19, IGKV4-1, and PRB3) with an AUC of 0.843. The present study reveals the transcriptome data-based differences between HL, DLBCL, and MCL, when combined with other clinical markers, may help the clinical diagnosis and prognosis.

The gap junction inhibitor INI-0602 attenuates mechanical allodynia and depression-like behaviors induced by spared nerve injury in rats.

Gap junctions (GJs) are novel molecular targets for pain therapeutics due to their pain-promoting function. INI-0602, a new GJ inhibitor, exerts a neuroprotective role, while its role in neuropathic pain is unclear. The objective was to investigate the analgesic role and mechanisms of INI-0602 in neuropathic pain induced by spared nerve injury (SNI), and whether INI-0602 attenuated pain-induced depression-like behaviors. Rats were randomly assigned to saline treatment groups (sham+NS and SNI+NS) or INI-0602 treatment groups (sham+INI-0602 and SNI+INI-0602). The von Frey test was used to assess pain behavior, and the sucrose preference test, the forced swimming test, and the tail suspension test were used to assess depression-like behaviors. Gap junction intercellular communication (GJIC) was measured by parachute assay. Western blots were used to determine the protein expression. In vitro, INI-0602 significantly suppressed GJIC by decreasing connexin43 and connexin32 expression. In vivo, INI-0602 significantly suppressed mechanical allodynia during initiation (7 days after SNI) and the maintenance phase (21 days after SNI) and simultaneously attenuated accompanying depression-like behaviors. Furthermore, INI-0602 markedly suppressed the activation of astrocytes and microglia on days 7 and 21 by reducing GJIC. Finally, INI-0602 reversed the changes in the brain-derived neurotrophic factor and Nr2b subunits of the N-methyl-D-aspartate receptor in SNI rats, suggesting that these effects of INI-0602 were related to its analgesic effect. Our findings demonstrated that blocking GJs with INI-0602 attenuated mechanical pain hypersensitivity and related depression-like behaviors in SNI rats by reducing glial activation.

Cx32 mediates cisplatin resistance in human ovarian cancer cells by affecting drug efflux transporter expression and activating the EGFR­Akt pathway.

Our previous study demonstrated that connexin 32 (Cx32) was upregulated and redistributed to the cytoplasm in A2780 human ovarian cancer cells with acquired resistance to cisplatin; this increased Cx32 feedback promoted cisplatin resistance. To further investigate the mechanism underlying Cx32­mediated cisplatin resistance, alterations in drug transporters, the DNA repair system and the anti­apoptotic signalling pathway were investigated by overexpressing or knocking down Cx32 in parental cells (A2780); cisplatin­resistant human ovarian cancer cells (A2780/CDDP) were also acquired. Upregulation of efflux transporters [multi­drug resistance protein 2 (MRP­2), ATPase copper transporting α (ATP7A) and ATPase copper transporting ß] and downregulation of the influx transporter copper uptake protein 1 mediated cisplatin resistance in A2780/CDDP cells. A2780/CDDP cells also exhibited increased expression of the DNA repair enzyme excision repair cross­complementation group 1 (ERCC1) and activation of the epidermal growth factor receptor (EGFR) signalling pathway. Small interfering RNA­mediated knockdown of Cx32 in A2780/CDDP cells decreased the expression of efflux transporters (MRP­2 and ATP7A). Knockdown of Cx32 in A2780/CDDP cells also decreased the expression of ERCC1, inhibited the activation of the EGFR signalling pathway and enhanced the cytotoxicity of cisplatin. When Cx32 was overexpressed in A2780 cells, an opposite effect on the expression of efflux transporters (MRP­2 and ATP7A) and the activation of the EGFR signalling pathway was observed, which resulted in insensitivity to cisplatin­induced apoptosis. Thus, Cx32 expression may induce cisplatin resistance by modulating drug efflux transporter expression and activating the EGFR­protein kinase B signalling pathway in ovarian cancer cells.

[Mechanism and Its Countermeasure of Hypomethylating Agent Resistance in Patients with Myelodysplastic Syndrome--Review].

Hypomethylating agents(HMA) currently are widely used in the treatment of myelodysplastic syndromes (MDS), provide a significant improvement in the treatment of MDS. However, resistance to HMA is an almost universal phenomenon. This review was focused on immune effects related to DNA methylation, and to explore the mechanism underlying HMA resistance involved in immune checkpoint pathways. However, the optimal role of checkpoint blockade therapy (CBT) and immune checkpoint pathways remain in HMA failure questionable. The better understanding of immune checkpoint pathways in resistance of HMA offers a compelling rationale to introduce CBT in patients as a novel treatment option. CBT is an established strategy in solid tumors with potential as an adjunctive therapy in hematologic malignancies, therefore, may alter the treatment landscape in MDS. The suitability and effectiveness of combining HMA with CBT need to be confirmed by the results of ongoing clinical trials, so as to find novel strategies to improve outcome after failure of HMA.

[Lymphocyte Count before First Consolidation Therapy Is A Predictor of Relapse free Survival in Acute Myeloid Leukemia].

OBJECTIVE: To investigate the effects of absolute lymphocyte count(ALC) before start of the first cycle of consolidation chemotherapy(CC) on the relapse free survival in the patients with acute myeloid leukemia(AML), so as to explore a simple and easy method for predicting AML relapse. METHODS: The clinical data of 132 patients with newly diagnosed AML (all non-acute promyelotic leukemia) from 2011 to 2017 were analyzed retrospectively. The 132 AML patients were treated with standard induction chemotherapy (IC) and consolidation chemotherapy (CC). According to lymphocyte count of patients before start of the first cycle of CC, the AML patients were divided into 2 group: high lymphocyte count group (H-Lym≥1.2×109/L) and low lymphocyte count group (L-Lym<1.2×109/L). The differences in ralapse rate and relapse-free survival between 2 groups were analyzed. RESULTS: Among 132 patients with AML, patients who could be valuated and were elicible for the study accounted for 65 (49.24%). The absolute leukocyte count, age, chromosome karyotypes before IC of patients did not show statistical difference between H-Lym group (40 cases) and L-Lym group (25 cases). Unvarvate analysis showed that the Low lymphocyte count and unfavorable chromosome karyotypes were poor prognostic factors for the relapse-free survival time, and there was significant difference between 2 groups (P<0.01). The relapse risk in patients of L-Lym group increased, the hazard ratio (HR)=3.01 (95% CI=1.55-4.98) (P<0.01). In multivariate analysis containing unfavorable prognostic karyotypes, this trend still existed (HR=2.52, 95% CI 1.28-9.98)(P<0.01). CONCLUSION: The AML patients with high lymphocyte count before the first CC have more long relapse free survival time suggesting that the lymphocyte count before the first CC may be prognostic factor for relapse free survival of AML patients.

[Predicting Therapeutic Response by Lymphocyte Level at 28th Day after DAC Treatment in Patients with MDS].

OBJECTIVE: To investigate a reliable clinical indication for predicting the therapeutic response of decitabine therapy in the patients with myelodysplastic syndromes (MDS). METHODS: The clinical efficacy of decitabine for 55 cases of MDS was analyzed retrospectively. According to the lymphocyte level at d28 after the first time treatment with decitabine, the patients were divided into high lymphocyte level group (H-Lym≥1.2×109/L) and low lymphocyte level group (L-Lym<1.2×109/L), and the overall response rate (ORR) and the progression-free survival (PFS) time in 2 groups were compared. RESULTS: As compared with L-Lym group, the ORR and PFS time in H-Lym group were significantly enhanced ï¼»(76.0% vs 50.0%) (P<0.05) and median time (15.7 months vs 8.5 months)(P<0.05), respectivelyï¼½;the ratio of platelet level ≥100×109/L in H-Lym group was very significantly higher than that in L-Lym group (72.0% vs 20.0%)(P<0.01). Multivariat analysis showed that the risk of disease progression in L-Lym group was 4.45-fold of H-Lym group (95% CI:1.58-12.59)(P<0.05). CONCLUSION: The patients with lymphocyte level ≥1.2×109/L at day 28 after the first time treatment with decitabine show the higher ORR and longer PFS time, therefore. the lymphocyte level at day 28 after first time treatment with decitabine can be used as an early clinical indicator for predecting the response to decitabine treatment.

[Molecular epidemiological study of measles viruses isolated in Qinghai Province during 2000-2011].

OBJECTIVE: To carry out the molecular epidemiological study of the wild-type measles virus isolated in Qinghai Province during 2000-2011, and provide a scientific basis for the measles elimination. METHODS: Measles viruses were isolated using B95a cell line or Vero/SLAM cell line from throat swabs collected from suspected measles cases during measles outbreak and sporadic in 6 prefectures during 2000-2011. The fragment of 696 nucleotides of N gene carboxy terminal was amplified by using RT-PCR methods. The PCR products were sequenced and analyzed. The phylogenetic tree was conducted with the viruses isolated in viruses from other province. RESULTS: Total 19 measles viruses were isolated during 2000-2011 in Qinghai province and all belong to genotype H1a. The results of phylogenetic tree showed that viruses in 2000-2005 and in 2009-2011 were distributed in two different lineages, and it revealed that these strains belonged to at least 2 viral transmission chains and the viruses circulated during 2000-2005 were not detected after 2005. CONCLUSION: Genotype H1a was the predominant genotype circulated in Qinghai province during 2000-2011. Qinghai measles virus strains had not evolved independently, but coevolved with the measles virus strains in other provinces in mainland China. The variation of important amino acid sites of measles virus should be continuous monitored and provide the scientific strategy for the measles elimination.

Magnetic Fe3O4@Au composite-enhanced surface plasmon resonance for ultrasensitive detection of magnetic nanoparticle-enriched α-fetoprotein.

Small molecules or analytes present at low concentrations are difficult to detect directly using conventional surface plasmon resonance (SPR) techniques because only small changes in the refractive index of the medium are typically induced by the binding of these analytes. Here, we present an amplification technique using core-shell Fe(3)O(4)@Au magnetic nanoparticles (MNPs) for an SPR bioassay. To evaluate this amplification effect, a novel SPR sensor based on a sandwich immunoassay was developed to detect α-fetoprotein (AFP) by immobilizing a primary AFP antibody (Ab(1)) on the surface of a 3-mercapto-1-propanesulfonate/chitosan-ferrocene/Au NP (MPS/CS-Fc/Au NP) film employing Fe(3)O(4)@Au-AFP secondary antibody conjugates (Fe(3)O(4)@Au-Ab(2)) as the amplification reagent. The stepwise fabrication of the biosensor was characterized using UV-vis spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. A calibration curve of Fe(3)O(4)@Au-Ab(2) conjugates amplification for AFP detection was obtained to yield a correlation in the range of 1.0-200.0 ng mL(-1) with a detection limit of 0.65 ng mL(-1), and a significant increase in sensitivity was therefore afforded through the use of Fe(3)O(4)@Au-Ab(2) conjugates as an amplifier. This magnetic separation and amplification strategy has great potential for the detection of other biomolecules of interest with low interference and high sensitivity by changing the antibody label used in the Fe(3)O(4)@Au-antibody conjugates.