Experimental study on the full cycle evolution of high-intensity atmospheric dc arc discharge from breakdown to extinguishment.

In this study, the spatiotemporal evolution of full cycle of high-intensity dc argon arc discharge at atmospheric pressure is investigated by using a transferred arc device, which is easy to be directly observed in the experiment. Combining the voltage and current waveforms with high-speed images, the full cycle evolution process of high-intensity atmospheric dc arc can be divided into five different stages: breakdown pulse stage, cathode heating stage, current climbing stage, stable arc discharge stage, and finally arc extinguishing stage. The characteristics of each different stage are analyzed in detail through the electrical properties, high-speed pictures, and spectroscopic measurements. The results show that the strong luminescence region develops from the vicinity of cathode and anode to the middle in the breakdown pulse stage, which is explained from the spatiotemporal evolution of distributions of excited argon atom and ions. The development velocity of emission intensity of argon ions is mainly determined by the dominant stepwise ionization process. Then the cathode heating stage appears with many bright and nonuniformly distributed light spots on the cathode surface, and the electron emission mechanism of cathode gradually changes to the thermionic emission as the surface temperature rises. With the increase of arc current, the discharge channel significantly expands, then becomes stable due to the increment of the Lorentz force. The characteristics of arc extinguishing stage are clarified in terms of the decay of charged particles density.

Apoptotic effect of novel pyrazolone-based derivative [Cu(PMPP-SAL)(EtOH)] on HeLa cells and its mechanism.

Pyrazolone complexes have strong anti-tumor and antibacterial properties, but the anti-tumor mechanism of pyrazolone-based copper complexes has not been fully understood. In this study, the possible mechanism and the inhibitory effect of a novel pyrazolone-based derivative compound [Cu(PMPP-SAL)(EtOH)] on human cervical cancer cells (HeLa cells) was investigated. [Cu(PMPP-SAL)(EtOH)] effectively inhibited proliferation of HeLa cells in vitro with an IC50 value of 2.082 after treatment for 72 h. Cell cycle analysis showed apoptosis was induced by blocking the cell cycle in the S phase. [Cu(PMPP-SAL)(EtOH)] promoted the loss of mitochondrial membrane potential, release of cytochrome c, PARP cleavage, and activation of caspase-3/9 in HeLa cells. Additionally, [Cu(PMPP-SAL)(EtOH)] inhibited the PI3K/AKT pathway and activated the P38/MAPK, and JNK/MAPK pathways. [Cu(PMPP-SAL)(EtOH)] also inhibited the phosphorylation of Iκ-Bα in the NF-κB pathway activated by TNF-α, thus restricting the proliferation of HeLa cells which were activated by TNF-α. In conclusion, [Cu(PMPP-SAL)(EtOH)] inhibited the growth of HeLa cells and induced apoptosis possibly via the caspase-dependent mitochondria-mediated pathway. These results suggest that [Cu(PMPP-SAL)(EtOH)] can be a potential candidate for the treatment of cervical cancer.

Synthesis, crystal structure and biological activity of two Mn complexes with 4-acyl pyrazolone derivatives.

In order to study the biological activities of transitional metal complexes based on 4-acyl pyrazolone derivatives, two Mn complexes [Mn(HLa)(La)]·(CH3CN)1.5·H2O (1) and [Mn2(Lb)2(µ-EtO)2(EtOH)2] (2) (H2La = N-(1-phenyl-3-methyl-4-benzoyl-5-pyrazolone)-2-thiophenecarboxylic acid hydrazide, H2Lb = N-(1-phenyl-3-methyl-4-propenylidene-5-pyrazolone)-2-thiophenecarboxylic acid hydrazide) have been synthesized and characterized. Single crystal X-ray diffraction analysis indicated that 1 is a mononuclear complex and 2 exhibits a dinuclear centrosymmetric structure. Binding of the complexes with Herring Sperm DNA (HS-DNA) showed that complexes 1 and 2 could intercalate to DNA with quenching constant of 5.3×10(4) M(-1) and 4.9×10(4) M(-1), respectively. The interactions of the complexes with bovine serum albumin (BSA) indicated that complexes 1 and 2 could quench the intrinsic fluorescence of BSA in a static quenching process. Further, the inhibitory effects of the complexes on the cell population growth of the human esophageal cancer Eca-109 cells and the cervical cancer HeLa cells were determined by MTT assay, which indicated that both 1 and 2 significantly inhibited the growth of Eca-109 and HeLa cells, the inhibitory activity of complex 1 is stronger than that of 2. We further observed that complex 1 inhibited the growth of HeLa cells through inducing the apoptosis and arresting cell cycle at S phase. Our results suggested that both complexes 1 and 2 have DNA- and protein-binding capacity and antitumor activity.

Modeling, docking and dynamics simulations of a non-specific lipid transfer protein from Peganum harmala L.

Non-specific lipid transfer proteins (ns-LTPs), ubiquitously found in various types of plants, have been well-known to transfer amphiphilic lipids and promote the lipid exchange between mitochondria and microbody. In this study, an in silico analysis was proposed to study ns-LTP in Peganum harmala L., which may belong to ns-LTP1 family, aiming at constructing its three-dimensional structure. Moreover, we adopted MEGA to analyze ns-LTPs and other species phylogenetically, which brought out an initial sequence alignment of ns-LTPs. In addition, we used molecular docking and molecular dynamics simulations to further investigate the affinities and stabilities of ns-LTP with several ligands complexes. Taken together, our results about ns-LTPs and their ligand-binding activities can provide a better understanding of the lipid-protein interactions, indicating some future applications of ns-LTP-mediated transport.

Serial expression of the truncated fragments of the nucleocapsid protein of CCHFV and identification of the epitope region.

The Crimean-congo hemorrhagic fever virus (CCHFV) is a geographically widespread fatal pathogen. Identification of the epitope regions of the virus is important for the diagnosis and epidemiological studies of CCHFV infections. In this study, expression vectors carrying series truncated fragments of the NP (nucleocapsid protein) gene from the S fragment of CCHFV strain YL04057 were constructed. The recombinant proteins were expressed in E.coli and purified for detection. The antigenic of the truncated fragments of NP was detected with a polyclonal serum (rabbit) and 2 monoclonal (mAbs) (14B7 and 43E5) against CCHFV by Western-blot analyses. The results showed that the three expressed constructs, which all contained the region 235AA to 305AA could be detected by mAbs polyclonal serum. The results suggest that region 235-305 aa of NP is a highly antigenic region and is highly conserved in the NP protein.

[Geography and host distribution of Crimean-Congo hemorrhagic fever in the Tarim Basin].

OBJECTIVE: To determine the infective status and natural distribution of Xinjiang hemorrhagic fever (XHF; Crimean-Congo hemorrhagic fever, CCHF) in ticks, rodents and livestock in the Tarim Basin. METHODS: The pathogenic materials of ticks or rodents' viscera and blood samples of sheep were inoculated into sucking mouse of 24 to 48-hour old. Materials with typical clinic symptoms were identified with RPHA and IFA. RT-PCR was taken to detect special S gene segment of Crimean-Congo hemorrhagic fever virus (CCHFV) in the objective material. RESULTS: All the samples of ticks, rodents' viscera and blood samples of sheep from 21 counties (cities) in the Tarim Basin were divided into 422 groups and inoculated into sucking mouse at laboratory. 49 materials with typical clinic symptoms were obtained. The morbidity rate with typical clinic XHF was high in Bachu, Yuli, Yutian and Ruoqiang. There were 43 samples identified with RPHA with 6 positive samples and positive rate of 1.4%. The materials with positive RPHA were found in Yuli, Luntai and Yutian. 42 samples were identified with IFA and 13 positive samples with the positive rate of 3.1%. The positive materials of IFA were found in Bachu, Yuli, Minfeng, Luntai and Yutian. 32 samples were detected with RT-PCR and there were 31 samples with special S gene segment of CCHFV (329- 548 nt). The positive materials was widely distributed in Aksu, Awat, Bachu, Luopu, Yuli, Minfeng, Qiemo, Ruoqiang, Luntai and Yutian. The highest infective rate was in Hyalomma asiaticum kozlovi, and followed by sheep. S gene segment was detected in viscera of M. meridianus. CONCLUSION: XHF relied on the river in the southern part of Xinjiang and distributed in the areas with Populus euphratica shrub in desert and oasis in the Tarim Basin. The main vector and host were Hyalomma asiaticum kozlovi. Livestock such as sheep, camel, L. yarkandensis, M. meridianus and Euchoreutes naso could serve as the deposited host of XHF.

[Molecular analysis on the S gene of three Crimean-Congo hemorrhagic fever virus strains in China].

OBJECTIVE: To compare the molecular characteristics of 3 Crimean-Congo hemorrhagic fever viruses(CCHFV) isolated in Xinjiang province. METHODS: YL05035, YT05099 and LT05146 were isolated in 2005 from Hyalomma ticks and viral RNA was extracted from suckling mouse brains infected with these three strains respectively. The polymerase chain reaction(PCR) products of S segments from the 3 strains of CCHFV were directly sequenced. RESULTS: The full-length'S RNA from the 3 strains of CCHFV all comprised 1673 nucleotides with ORF of them including 1449 nucleotides and encoding a protein which comprised 482 amino acids in a viral complementary sense. The sequences indicated that the three strains of CCHFV isolated from ticks in Xinjiang province were highly homologenic. Data from the phylogenetic analysis showed that the obtained sequences were identical. The homology between 3 strains of CCHFV was 99.5%. Their homologies compared with that of the other strains isolated from other region of Xinjiang were also high at nucleotide levels (92.7%-99.8%). The three strains which were clustered together with 7001 strain and 79121 strain (isolated from patient and rat in Xinjiang respectively) was only different by 2%-3%. The genetic difference from the prototype CCHFV Nigerian strain IBAR10200 was 13%. In comparison, the Nigerian CCHFV tick isolate was more divergent when compared with the reference China strains 66019 and with the three variants mentioned above. CONCLUSION: The CCHFV isolated from China comprised a group of genetically high conserved strains.