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Articles by S. Wang
Total Records ( 9 ) for S. Wang
  L Li , J Xie , M Zhang and S. Wang
 

Homocysteine (Hcy) can induce proliferation of vascular smooth muscle cells (VSMCs), which is a key event in the genesis of the lesions of atherosclerosis. Insulin-like growth factor 2 (IGF2) and H19 are two important regulating molecules of cell proliferation. The role of Hcy in the proliferation of smooth muscle cell by regulating IGF2 and H19 has not been shown or analyzed so far. This study aims to investigate the potential impact of Hcy on gene imprinting of IGF2 and H19. Cultured human umbilical VSMCs were treated with different concentrations of Hcy. The DNA methylation status of VSMCs was assayed by nested methylation-specific polymerase chain reaction (PCR). The mRNA levels of H19, IGF2, and CCCTC-binding factor (CTCF) were detected by reverse transcription PCR, and the protein expression of IGF2 by Western blotting. The results showed that the Hcy treatment resulted in hypomethylation of the sixth CTCF-binding site upstream of H19 of VSMCs. The expression of H19 was increased, whereas the IGF2 mRNA and protein were decreased, the CTCF expression increased with the increase in Hcy concentration. These data indicated that Hcy could induce hypomethylation of the sixth CTCF-binding sites upstream of H19, which is an important regulating area for the imprinting expression of IGF2 and H19. The increased CTCF expression may be a potential mechanism for the demethylation modification of DNA, which resulted from the Hcy treatment.

  Z. DING , Y. XU , H. ZHANG , S. WANG , W. CHEN and Z. SUN
  An experiment was conducted in the laboratory to investigate the effects of additive ratios of docosahexaenoic acid (DHA) to eicosapentaenoic acid (EPA) on the growth and survival of cobia (Rachycentron canadum) juveniles from August to October 2005. Three hundred and eighty cobia juveniles (56 days of age, body weight 6.9 ± 0.1 g, body length 9.2 ± 0.1 cm) were selected and 20 of them were freely taken for initial sample analysis in the week 0. Additional 360 juveniles were randomly assigned into eight groups with triplicate, total 24 tanks with 15 fish each. Cobia juveniles were reared in glass-steel tanks (200-L volume per tank) using filtered seawater with temperature 26–30.5 °C, salinity 25.4–33.0 g L−1 and pH 7.8–8.0. Cobia juveniles were fed for 8 weeks using seven treatment diets (D-1 to D-7) with the same amount of DHA and EPA (15.0 ± 1.2 g kg−1 of dried diet), but varying ratios of DHA to EPA (0.9, 1.1, 1.3, 1.5, 1.7, 1.9, 2.1, respectively) and a control diet (D-0, DHA + EPA = 8.0 g kg−1 of dried diet, DHA/EPA = 1.3). Five juveniles per tank were randomly taken for sample analysis at the end of weeks 4 and 8, respectively. The highest protein efficiency rate (PER; 1.5 in mean), average body weight (BW; 73.3 g per fish in mean) and the lowest feed conversion ratio (FCR; 1.6 in mean) were obtained in cobia juveniles fed the control diet at the end of week 8. These parameters were significantly different (P < 0.05) among juveniles fed the control and treatment diets; however, no significant difference (P > 0.05) was found among juveniles fed the treatment diets evaluated in this study. It was concluded that the survival and growth of cobia juveniles were not greatly influenced by additive ratios of DHA to EPA in our experimental conditions.
  A.M. Fouad , Y. Li , W. Chen , D. Ruan , S. Wang , W. Xie , Y.C. Lin and C.T. Zheng
  Objective: Manganese (Mn) is a crucial trace element for poultry nutrition because it has multiple physiological functions. Thus, the main goal of this study was to evaluate the effects of dietary Mn supplementation on laying performance, egg quality and antioxidant status in Shanma laying ducks. Methodology: Five hundred and four Shanma laying ducks, at 17 weeks of age, were randomly assigned to 7 treatments, with 6 replicates per treatment and 12 ducks per replicate. Birds were fed the same basal diet, which was supplemented with 0.0 (control), 15, 30, 45, 60, 75 or 90 mg Mn/kg in the form of Mn-sulfate. Results: Results showed that dietary Mn supplementation did not affect egg production, egg weight, feed conversion ratio, egg mass, egg quality, tibia characteristics, total antioxidant capacity, copper-zinc superoxide dismutase or lipid peroxidation (malondialdehyde), but supplementing 90 mg Mn/kg diet significantly (p<0.05) improved the activities of total superoxide dismutase, Mn-containing superoxide dismutase and increased Mn content in egg yolk compared with the control group. Conclusion: These results indicate that corn-soybean meal diet containing sufficient amount of Mn for laying performance and egg quality in Shanma laying ducks under the conditions of current experiment, but adding 90 mg Mn/kg basal diet is required to improve the activities of Mn-containing superoxide dismutase and total superoxide dismutase and elevate Mn content in their egg yolk.
  C. S Huang , C. H Hung and S. Wang
 

In this paper we present a convergence analysis for a fitted finite-volume discretization method for the two-dimensional Black–Scholes equation arising in the Hull–White model for pricing European options with stochastic volatility. We first formulate the finite-volume method as a nonconforming Petrov–Galerkin finite–element method with each basis function of the trial space being determined by a set of two-point boundary-value problems defined on element edges. We then show that the bilinear form of the finite-element method is coercive and continuous. Finally we establish an upper bound of order $$\mathrm{O}\left(h\right)$$ on the discretization error of method, where h denotes the mesh parameter of the discretization.

  S. Wang and F.W. Edens
  Large comb (LC) broiler cockerels, with high levels of testosterone and corticosterone, survived acute heat stress while small comb (SC) cockerels, with low levels of testosterone and corticosterone were more susceptible to heat stress and suffered higher mortality rates. This phenomenon was related to the greater ability of the LC and the lesser ability of the SC broilers to synthesize heat shock proteins (HSP), which are involved in acquisition and maintenance of thermotolerance. When broiler cockerels, selected for LC or SC, were exposed to acute heat stress, the synthesis of three HSP-hsp-90, hsp-70 and hsp-23 by peripheral blood leukocytes was elevated in both groups of broilers, but LC chickens responded with higher HSP synthesis than did SC chickens. One of the normal cellular proteins, actin, was depressed during the heat stress over 105 minutes. To determine whether steroid hormones, testosterone and corticosterone, influence the expression of HSP in chickens, exogenous testosterone and corticosterone were implanted in LC capons and metyrapone-fed LC capons, respectively. The plasma testosterone was raised in the testosterone-treated capons, was depressed in the capons and metyrapone-fed capons and was indicated indirectly by growth rate of the comb. The heat-induced synthesis of HSP was depressed by caponization and depressed further in the capons fed metyrapone, which blocks the synthesis pathway of endogenous corticosterone in adrenal glands. The exogenous testosterone and to a lesser degree, corticosterone, stimulated the expression of HSP in heat-stressed capons. The results suggested that the steroid hormones, testosterone and corticosterone, are involved in the expression of HSP, which are associated with acquired and maintained thermoresistance in domestic chickens.
  A.M. Fouad , W. Chen , D. Ruan , S. Wang , W.G. Xia and C.T. Zheng
  Modern strains of poultry have been produced to meet the demands of consumers in terms of quantity and they are affected by problems associated with immunity (sensitivity to infection with different diseases), stressors (high sensitivity to different stressors) and product quality (meat and egg quality). In particular, heat stress (HS) negatively affects the productive performance, meat yield, egg yield, meat quality (visual appearance and chemical characteristics), egg quality (internal and external), reproductive performance, intestinal functions and immune response. In addition, there is increased awareness among consumers of the quality of food and the industry must aim to satisfy the higher requirements of consumers. Thus, there is increased pressure on poultry producers to improve their production quantity and quality. As a consequence, it is important to know how HS affects the meat quality, egg quality, immune organs, intestinal functions and reproductive organs in order to protect against any negative effects. In addition, it is essential to determine the roles of nutritional factors and the possibility of using them to overcome the negative effects of HS. This review summarizes current research in these areas.
  B Zhang , D. V Faller and S. Wang
 

An intractable problem impeding breast cancer treatment by the most frequently prescribed endocrine therapy tamoxifen is the inevitable development of resistance, and the molecular mechanisms underlying this loss of responsiveness by breast cancers have been under intense investigation but are not yet fully elucidated. Our recent reports demonstrated that the tumor suppressor heavily methylated in cancers 1 (HIC1) plays an essential role in growth suppression mediated by external stimuli. We report here that novel tumor suppressor HIC1 is required for growth suppression by estrogen antagonists in breast cancer cells. We also find that HIC1 expression is dramatically induced by exposure to estrogen antagonists in sensitive cells, via a c-Jun N-terminal kinase 1 (JNK1) and prohibitin-mediated signaling pathway. This induction is lost in spontaneously antagonist-resistant breast cancer cells. Furthermore, reintroducing HIC1 into resistant breast cancer cells restored their sensitivity to the estrogen antagonists, indicating the existence of a novel regulatory mechanism for growth control of breast cancer cells.

  A.M. Fouad , Y. Li , W. Chen , D. Ruan , S. Wang , W.G. Xie , Y.C. Lin and C.T. Zheng
  This study was designed to investigate the influences of dietary copper (Cu) on laying performance, egg quality, plasma total cholesterol (TC), high-density lipoprotein cholesterol (HDLC) and low density lipoprotein-cholesterol (LDLC) concentrations in Shanma laying ducks. A total of 504 egg laying ducks aged 17 week were randomly allotted to seven groups (twelve ducks per replicate and six replicates each treatment). The control group was fed a corn-soybean meal diet, whereas the treatment groups were fed corn-soybean meal diets supplemented with 4, 8, 12, 16, 20, or 24 mg Cu-sulfate/kg. Egg production, egg weight, egg mass, feed conversion ratio, broken egg rate, abnormal egg rate, Haugh unit, yolk color, albumen height, eggshell weight, eggshell percent, eggshell breaking strength, eggshell thickness, plasma TC, HDLC and LDLC concentrations did not appear response to dietary Cu levels. Our results indicated that corn-soybean meal diet containing sufficient amount of Cu for laying performance and egg quality in laying ducks under the conditions of current experiment. Also, laying performance, plasma TC, HDLC, LDLC concentrations and egg quality were not sensitive traits to low levels of Cu.
  M Yuan , Z Chu , X Li , C Xu and S. Wang
 

The fully recessive disease resistance (R) gene xa13, which mediates race-specific resistance to Xanthomonas oryzae pv. oryzae (Xoo), encodes a plasma membrane protein that differs by one amino acid from that encoded by its dominant (susceptible) allele Xa13. The molecular mechanism of xa13-mediated resistance is largely unknown. Here we show that, compared with its dominant allele, expressional non-reaction of xa13 to Xoo infection, not its protein composition, is the key factor for xa13-mediated resistance. We used the promoter (PXa13) of the dominant Xa13, which was induced by only the incompatible Xoo strain for xa13, to regulate xa13 and xa13Leu49 (a natural recessive allele of xa13) in the rice line IRBB13 carrying xa13. The transgenic plants showed the same level of susceptibility and bacterial growth rate as those of the rice line carrying dominant Xa13, accompanied by the induced accumulation of xa13 or xa13Leu49 proteins. Constitutive expression of dominant XA13 or different xa13 proteins (xa13, xa13Leu49, xa13Ala85 or xa13Val184) in IRBB13 had no effect on Xoo infection in the transgenic plants. These results suggest that race-specific pathogen-induced Xa13 expression is critical for infection. Thus, xa13 stands out from other R genes in that its functions in disease resistance are due to only the loss of pathogen-induced transcriptional motivation caused by natural selection.

 
 
 
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