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Articles by Chang Liu
Total Records ( 7 ) for Chang Liu
  Ling Zhao , Kaiyu Wang , Dexiang Wang , Chang Liu and Wei Zhang
  Microwave-assisted extraction was investigated for extraction of polysaccharides from Catathelasma ventricosum using Response Surface Methodology (RSM). The effects of operating conditions (extraction time, microwave power and ratio of water to raw material) on the extraction yield of polysaccharides were studied. A Box-Behnken Design was used for experimental design and analysis of the results to obtain the optimal processing parameters. Among the three extraction parameters, the microwave power was the most significant factor to affect the yield of polysaccharides from Catathelasma ventricosum. In addition, microwave power and extraction time had significant interaction effects. A mathematical model with high determination coefficient was gained and could be employed to optimize polysaccharides extraction and the optimal conditions were extraction time 5 min, microwave power 420 W, ratio of water to raw material 25:1. Under these conditions, the experimental yield of polysaccharide was 7.83±0.19% which was close to the predicted value.
  Wei Wang , Funing Chen , Zhihao Wang and Chang Liu
  The employment is a more complex economic and social phenomenon. It can be the basic premise of government austerity to make a real and objective analysis and judgment on the employment states and to resolve to expand employment channels and measures. The adjustment and upgrading of industrial structure was the key factors which directly impact on the employment states in Harbin. Therefore, the study applied the statistical method, factor analysis, to analyze and evaluate the employment states of three major industries deeply and summed up the personality characteristics and the causes of employment states, based on the sixth census data of bureau statistics in Harbin in 2010. The results could provide the scientific basis to develop and implement employment policies for government decision.
  Xian Gao , Lixia Zhou , Ganzhen Deng , Chang Liu , Chengye Li , Changwei Qiu and Xiuli Peng
  To determine which aerobic bacteria exert a marked effect on Cystic Endometrial Hyperplasia-Pyometra complex (CEH-P) and to determine from where these bacteria originate. About 48 privately owned bitches were diagnosed with CEH-P. Healthy vagina and uterine samples were obtained with cotton pledgets and cumulative uterine fluids from CEH-P cysts were collected with a syringe in utero to isolate and identify aerobic bacterial. A total of 99 isolates were identified and the primary aerobe in the CEH-P bitches was found to be Escherichia coli (33/99). The levels of estrode in bitches with endometritis and in bitches with pyometra and estrus were higher than the levels in diestrus bitches (p<0.01). When ranked according to the levels of progesterone in a descending order (i.e., from high to low levels), the ranking was bitches with pyometra, bitches with endometritis, bitches in estrus and bitches in diestrus. These results suggest that in addition to common pathogenic bacteria differential in every area, casual bacterial contamination invariably occurred in bitches with CEH-P and the primary infection ascended from the vagina when the cervix was open. The researchers also inferred that both estrode and progesterone levels in CEH-P bitches were increased relative to the levels in healthy bitches and were even higher than that of the levels observed in estrus bitches. Estrode and progesterone pretreatment and uterine mucosa damage were interpreted as the preconditions for bacterial infection. The hormone levels in CEH-P bitches were similar to the endocrinal characteristics of peripartum bitches.
  Chang Liu , Zhihui Zhaoa , Wenlin Bai , Boxing Sun , Yonghong Zhang and Runjun Yang
  Insulin-Like Growth Factor 1 (IGF-1) is a single copy gene. It generates several IGF-1 mRNA variants due to alternative splicing. Spliced variants of IGF-1 being some small peptides derived from spliced variants of IGF-1 have critical roles in cell metabolism and growth of various vertebrate species. Porcine IGF-1 gene has two promoters and the existence of Exon 6 has been confirmed in Songliao Black pig in the laboratory. The aims of the present study were to identify new spliced variants of IGF-1 gene including Exon 5 and to investigate their expression profile in different tissues of Songliao Black pig. The cDNAs of two new spliced variants of IGF-1 gene were cloned by RACE. These two variants were named Class I IGF-1-Eb and Class II IGF-1-Eb, respectively. The Class I IGF-1-Eb contains an Open Reading Frame (ORF) of 564 bp encoding 187 amino acids (GenBank Accession No. FJ914497). The Class II IGF-1-Eb contains an ORF of 516-bp encoding 171 amino acids (GenBank Accession No. FJ914498). Tissue distributions of mRNAs of Class I IGF-1-Eb and Class II IGF-1-Eb were investigated in Songliao Black pig by semi-quantitative RT-PCR. Both of the new mRNA variants were expressed in a variety of tissues. Class I IGF-1-Eb mRNA was more abundant than Class II IGF-1-Eb mRNA in most tissues except for duodenum and longissimus muscle (p<0.05).
  Yu Zhonggen and Chang Liu
  The threshold hypothesis is well-known in the field of language forgetting. This study attempts to validate this hypothesis in computer aided English language forgetting among tertiary students in China. The data were collected from the test scores of 38 participants who had received computer aided English education and had not learned English for two years. The results indicated that participants who failed to pass CET 6 presented significant language forgetting regarding listening (t = 3.21, p = 0.02), reading (t = 5.14, p = 0.01), writing (t = 2.15, p = 0.03) and cloze (t = 7.25, p = 0.01). By contrast, participants who passed CET 6 showed no significant language forgetting as to listening (t = 2.14, p = 0.06) and cloze (t = 2.72, p = 0.42). Nevertheless, they showed significant language forgetting as to writing (t = 2.83, p = 0.01). In addition, it was somewhat surprising to find that they did not show significant language forgetting in reading comprehension. In contrast, their reading skills significantly gained after two years break (t = 2.82, p = 0.03).
  Peirong Jiao , Guobin Tian , Yanbing Li , Guohua Deng , Yongping Jiang , Chang Liu , Weilong Liu , Zhigao Bu , Yoshihiro Kawaoka and Hualan Chen
  In this study, we explored the molecular basis determining the virulence of H5N1 avian influenza viruses in mammalian hosts by comparing two viruses, A/Duck/Guangxi/12/03 (DK/12) and A/Duck/Guangxi/27/03 (DK/27), which are genetically similar but differ in their pathogenicities in mice. To assess the genetic basis for this difference in virulence, we used reverse genetics to generate a series of reassortants and mutants of these two viruses. We found that a single-amino-acid substitution of serine for proline at position 42 (P42S) in the NS1 protein dramatically increased the virulence of the DK/12 virus in mice, whereas the substitution of proline for serine at the same position (S42P) completely attenuated the DK/27 virus. We further demonstrated that the amino acid S42 of NS1 is critical for the H5N1 influenza virus to antagonize host cell interferon induction and for the NS1 protein to prevent the double-stranded RNA-mediated activation of the NF-ĸB pathway and the IRF-3 pathway. Our results indicate that the NS1 protein is critical for the pathogenicity of H5N1 influenza viruses in mammalian hosts and that the amino acid S42 of NS1 plays a key role in undermining the antiviral immune response of the host cell.
  Chang Liu , Maho Takahashi , Yanping Li , Shuang Song , Tara J. Dillon , Ujwal Shinde and Philip J. S. Stork
  Exchange proteins activated by cAMP (cyclic AMP) 2 (Epac2) is a guanine nucleotide exchange factor for Rap1, a small G protein involved in many cellular functions, including cell adhesion, differentiation, and exocytosis. Epac2 interacts with Ras-GTP via a Ras association (RA) domain. Previous studies have suggested that the RA domain was dispensable for Epac2 function. Here we show for the first time that Ras and cAMP regulate Epac2 function in a parallel fashion and the Ras-Epac2 interaction is required for the cAMP-dependent activation of endogenous Rap1 by Epac2. The mechanism for this requirement is not allosteric activation of Epac2 by Ras but the compartmentalization of Epac2 on the Ras-containing membranes. A computational modeling is consistent with this compartmentalization being a function of both the level of Ras activation and the affinity between Ras and Epac2. In PC12 cells, a well-established model for sympathetic neurons, the Epac2 signaling is coupled to activation of mitogen-activated protein kinases and contributes to neurite outgrowth. Taken together, the evidence shows that Epac2 is not only a cAMP sensor but also a bona fide Ras effector. Coincident detection of both cAMP and Ras signals is essential for Epac2 to activate Rap1 in a temporally and spatially controlled manner.
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