Asian Science Citation Index is committed to provide an authoritative, trusted and significant information by the coverage of the most important and influential journals to meet the needs of the global scientific community.  
ASCI Database
308-Lasani Town,
Sargodha Road,
Faisalabad, Pakistan
Fax: +92-41-8815544
Contact Via Web
Suggest a Journal
 
Articles by H Sun
Total Records ( 9 ) for H Sun
  S. G Lindell , M. L Schwandt , H Sun , J. D Sparenborg , K Bjork , J. W Kasckow , W. H Sommer , D Goldman , J. D Higley , S. J Suomi , M Heilig and C. S. Barr
 

Context  Neuropeptide Y (NPY) counters stress and is involved in neuroadaptations that drive escalated alcohol drinking in rodents. In humans, low NPY expression predicts amygdala response and emotional reactivity. Genetic variation that affects the NPY system could moderate stress resilience and susceptibility to alcohol dependence.

Objective  To determine whether functional NPY variation influences behavioral adaptation to stress and alcohol consumption in a nonhuman primate model of early adversity (peer rearing).

Design  We sequenced the rhesus macaque NPY locus (rhNPY) and performed in silico analysis to identify functional variants. We performed gel shift assays using nuclear extract from testes, brain, and hypothalamus. Levels of NPY in cerebrospinal fluid were measured by radioimmunoassay, and messenger RNA levels were assessed in the amygdala using real-time polymerase chain reaction. Animals were exposed to repeated social separation stress and tested for individual differences in alcohol consumption. Animals were genotyped for –1002 T > G, and the data were analyzed using analysis of variance.

Setting  National Institutes of Health Animal Center.

Subjects  Ninety-six rhesus macaques.

Main Outcome Measure  Behavior arousal during social separation stress and ethanol consumption.

Results  The G allele altered binding of regulatory proteins in all nuclear extracts tested, and –1002 T > G resulted in lower levels of NPY expression in the amygdala. Macaques exposed to adversity had lower cerebrospinal fluid NPY levels and exhibited higher levels of arousal during stress, but only as a function of the G allele. We also found that stress-exposed G allele carriers consumed more alcohol and exhibited an escalation in intake over cycles of alcohol availability and deprivation.

Conclusions  Our results suggest a role for NPY promoter variation in the susceptibility to alcohol use disorders and point to NPY as a candidate for examining gene x environment interactions in humans.

  H Sun , K Lemmens , T. V. d Bulcke , K Engelen , B. D Moor and K. Marchal
 

Motivation: We developed ViTraM, a tool that allows visualizing overlapping transcriptional modules in an intuitive way. By visualizing not only the genes and the experiments in which the genes are co-expressed, but also additional properties of the modules such as the regulators and regulatory motifs that are responsible for the observed co-expression, ViTraM can assist in the biological analysis and interpretation of the output of module detection tools.

  X Zheng , D Lian , A Wong , M Bygrave , T. E Ichim , M Khoshniat , X Zhang , H Sun , T De Zordo , J. C Lacefield , B Garcia , A. M Jevnikar and W. P. Min
 

Background— Ischemia/reperfusion injury is a major factor in graft quality and subsequent function in the transplantation setting. We hypothesize that the process of RNA interference may be used to "engineer" a graft to suppress expression of genes associated with inflammation, apoptosis, and complement, which are believed to cause ischemia/reperfusion injury. Such manipulation of pathological gene expression may be performed by treatment of the graft ex vivo with small interfering RNA (siRNA) as part of the preservation procedure.

Methods and Results— Heart grafts from BALB/c mice were preserved in UW solution (control) or UW solution containing siRNAs targeting tumor necrosis factor-, C3, and Fas genes (siRNA solution) at 4°C for 48 hours and subsequently transplanted into syngeneic recipients. Tumor necrosis factor-, C3, and Fas genes were elevated by ischemia/reperfusion injury after 48 hours of preservation in UW solution. Preservation in siRNA solution knocked down gene expression at the level of messenger RNA and protein in the grafts after transplantation. All grafts preserved in siRNA solution showed strong contraction, whereas grafts preserved in control solution demonstrated no detectable contraction by high-frequency ultrasound scanning. siRNA solution–treated organs exhibited improved histology and diminished neutrophil and lymphocyte infiltration compared with control solution–treated organs. Furthermore, the treated heart grafts retained strong beating up to the end of the observation period (>100 days), whereas all control grafts lost function within 8 days.

Conclusion— Incorporation of siRNA into organ storage solution is a feasible and effective method of attenuating ischemia/reperfusion injury, protecting cardiac function, and prolonging graft survival.

  S Hu , Z Zheng , X Yuan , W Wang , Y Song , H Sun and J. Xu
 

Background— Despite its widespread use and short-term efficacy, substantial uncertainty remains about the long-term outcomes and cost-effectiveness of off-pump coronary artery bypass (OPCAB).

Methods and Results— A retrospective review of prospectively collected data was conducted of 6665 consecutive patients undergoing isolated coronary artery bypass graft (CABG) at our institution during 1999 to 2006. All patients were followed up until September 30, 2008. Short- and long-term outcomes were compared between OPCAB and conventional CABG. The 2 main long-term outcome measures were repeat revascularization and the composite outcome of major vascular events. Cost comparison at 2 years in a propensity-matched sample during follow-up was also a study interest. The overall mean baseline age was 60.3±8.6 years, and 17.0% were women. Compared with conventional CABG, patients who underwent OPCAB had lower rates of atrial fibrillation (P=0.003) and requirements for blood transfusion (P=0.03) and ventilation time >24 hours (P<0.001). After an average of 4.5 years of follow-up, the rates of repeat revascularization (adjusted hazard ratio, 1.40; 95% confidence interval, 1.03 to 1.89) and major vascular events (adjusted hazard ratio, 1.23; 95% confidence interval, 1.09 to 1.39) were significantly higher in the OPCAB than the conventional CABG group. At 2 years, OPCAB was associated with increased additional direct costs per patient compared with conventional CABG and had a similar survival rate.

Conclusions— Compared with conventional CABG, OPCAB is associated with small short-term gain but increased long-term risks of repeat revascularization and major vascular events, especially among high-risk patients. Moreover, OPCAB consumes more resources and is less cost-effective in the long run.

  R. W.K Chiu , H Sun , R Akolekar , C Clouser , C Lee , K McKernan , D Zhou , K. H Nicolaides and Y.M. D. Lo
 

Background: Noninvasive prenatal diagnosis of trisomy 21 (T21) has recently been shown to be achievable by massively parallel sequencing of maternal plasma on a sequencing-by-synthesis platform. The quantification of several other human chromosomes, including chromosomes 18 and 13, has been shown to be less precise, however, with quantitative biases related to the chromosomal GC content.

Methods: Maternal plasma DNA from 10 euploid and 5 T21 pregnancies was sequenced with a sequencing-by-ligation approach. We calculated the genomic representations (GRs) of sequenced reads from each chromosome and their associated measurement CVs and compared the GRs of chromosome 21 (chr21) for the euploid and T21 pregnancies.

Results: We obtained a median of 12 x 106 unique reads (21% of the total reads) per sample. The GRs deviated from those expected for some chromosomes but in a manner different from that previously reported for the sequencing-by-synthesis approach. Measurements of the GRs for chromosomes 18 and 13 were less precise than for chr21. z Scores of the GR of chr21 were increased in the T21 pregnancies, compared with the euploid pregnancies.

Conclusions: Massively parallel sequencing-by-ligation of maternal plasma DNA was effective in identifying T21 fetuses noninvasively. The quantitative biases observed among the GRs of certain chromosomes were more likely based on analytical factors than biological factors. Further research is needed to enhance the precision for measuring for the representations of chromosomes 18 and 13.

  A Liu , A. D Patterson , Z Yang , X Zhang , W Liu , F Qiu , H Sun , K. W Krausz , J. R Idle , F. J Gonzalez and R. Dai
 

Fenofibrate, widely used for the treatment of dyslipidemia, activates the nuclear receptor, peroxisome proliferator-activated receptor . However, liver toxicity, including liver cancer, occurs in rodents treated with fibrate drugs. Marked species differences occur in response to fibrate drugs, especially between rodents and humans, the latter of which are resistant to fibrate-induced cancer. Fenofibrate metabolism, which also shows species differences, has not been fully determined in humans and surrogate primates. In the present study, the metabolism of fenofibrate was investigated in cynomolgus monkeys by ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS)-based metabolomics. Urine samples were collected before and after oral doses of fenofibrate. The samples were analyzed in both positive-ion and negative-ion modes by UPLC-QTOFMS, and after data deconvolution, the resulting data matrices were subjected to multivariate data analysis. Pattern recognition was performed on the retention time, mass/charge ratio, and other metabolite-related variables. Synthesized or purchased authentic compounds were used for metabolite identification and structure elucidation by liquid chromatographytandem mass spectrometry. Several metabolites were identified, including fenofibric acid, reduced fenofibric acid, fenofibric acid ester glucuronide, reduced fenofibric acid ester glucuronide, and compound X. Another two metabolites (compound B and compound AR), not previously reported in other species, were characterized in cynomolgus monkeys. More importantly, previously unknown metabolites, fenofibric acid taurine conjugate and reduced fenofibric acid taurine conjugate were identified, revealing a previously unrecognized conjugation pathway for fenofibrate.

  A Liu , A. D Patterson , Z Yang , X Zhang , W Liu , F Qiu , H Sun , K. W Krausz , J. R Idle , F. J Gonzalez and R. Dai
 

Fenofibrate, widely used for the treatment of dyslipidemia, activates the nuclear receptor, peroxisome proliferator-activated receptor . However, liver toxicity, including liver cancer, occurs in rodents treated with fibrate drugs. Marked species differences occur in response to fibrate drugs, especially between rodents and humans, the latter of which are resistant to fibrate-induced cancer. Fenofibrate metabolism, which also shows species differences, has not been fully determined in humans and surrogate primates. In the present study, the metabolism of fenofibrate was investigated in cynomolgus monkeys by ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS)-based metabolomics. Urine samples were collected before and after oral doses of fenofibrate. The samples were analyzed in both positive-ion and negative-ion modes by UPLC-QTOFMS, and after data deconvolution, the resulting data matrices were subjected to multivariate data analysis. Pattern recognition was performed on the retention time, mass/charge ratio, and other metabolite-related variables. Synthesized or purchased authentic compounds were used for metabolite identification and structure elucidation by liquid chromatographytandem mass spectrometry. Several metabolites were identified, including fenofibric acid, reduced fenofibric acid, fenofibric acid ester glucuronide, reduced fenofibric acid ester glucuronide, and compound X. Another two metabolites (compound B and compound AR), not previously reported in other species, were characterized in cynomolgus monkeys. More importantly, previously unknown metabolites, fenofibric acid taurine conjugate and reduced fenofibric acid taurine conjugate were identified, revealing a previously unrecognized conjugation pathway for fenofibrate.

  M Kotaka , R Kong , I Qureshi , Q. S Ho , H Sun , C. W Liew , L. P Goh , P Cheung , Y Mu , J Lescar and Z. X. Liang
 

The biosynthesis of the enediyne moiety of the antitumor natural product calicheamicin involves an iterative polyketide synthase (CalE8) and other ancillary enzymes. In the proposed mechanism for the early stage of 10-membered enediyne biosynthesis, CalE8 produces a carbonyl-conjugated polyene with the assistance of a putative thioesterase (CalE7). We have determined the x-ray crystal structure of CalE7 and found that the subunit adopts a hotdog fold with an elongated and kinked substrate-binding channel embedded between two subunits. The 1.75-Å crystal structure revealed that CalE7 does not contain a critical catalytic residue (Glu or Asp) conserved in other hotdog fold thioesterases. Based on biochemical and site-directed mutagenesis studies, we proposed a catalytic mechanism in which the conserved Arg37 plays a crucial role in the hydrolysis of the thioester bond, and that Tyr29 and a hydrogen-bonded water network assist the decarboxylation of the β-ketocarboxylic acid intermediate. Moreover, computational docking suggested that the substrate-binding channel binds a polyene substrate that contains a single cis double bond at the C4/C5 position, raising the possibility that the C4=C5 double bond in the enediyne moiety could be generated by the iterative polyketide synthase. Together, the results revealed a hotdog fold thioesterase distinct from the common type I and type II thioesterases associated with polyketide biosynthesis and provided interesting insight into the enediyne biosynthetic mechanism.

 
 
 
Copyright   |   Desclaimer   |    Privacy Policy   |   Browsers   |   Accessibility