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1.  MicroRNA-424 Is Down-Regulated in Hepatocellular Carcinoma and Suppresses Cell Migration and Invasion through c-Myb 
PLoS ONE  2014;9(3):e91661.
Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related mortality worldwide. MicroRNAs (miRNAs) are important regulators of multiple cellular processes, and the aberrant miRNAs expressions have been observed in different types of cancer including HCC. Their pathysiologic role and their relevance to tumorigenesis are still largely unknown. In this study, we demonstrated the down-regulation of miR-424 in HCC cell lines and tissues by quantitative RT-PCR analyses. Overexpression of miR-424 reduced the HCC cell prolifetation, migration, and invasion. Conversely, inhibiton of miR-424 expression significantly accelerated the cell proliferation, migration, and invasion. In addition, we further identified c-Myb as a functional downstream target of miR-424 by directly targeting the 3′UTR of c-Myb. Furthermore, overexpression of c-Myb impaired miR-424-induced inhibition of proliferation and invasion in HCC cells. Our results demonstrated that miR-424 was involved in tumorigenesis of HCC at least in part by suppression of c-Myb.
PMCID: PMC3968007  PMID: 24675898
2.  Rapid Diagnosis of Aneuploidy Using Segmental Duplication Quantitative Fluorescent PCR 
PLoS ONE  2014;9(3):e88932.
The aim of this study was use a simple and rapid procedure, called segmental duplication quantitative fluorescent polymerase chain reaction (SD-QF-PCR), for the prenatal diagnosis of fetal chromosomal aneuploidies. This method is based on the co-amplification of segmental duplications located on two different chromosomes using a single pair of fluorescent primers. The PCR products of different sizes were subsequently analyzed through capillary electrophoresis, and the aneuploidies were determined based on the relative dosage between the two chromosomes. Each primer set, containing five pairs of primers, was designed to simultaneously detect aneuploidies located on chromosomes 21, 18, 13, X and Y in a single reaction. We applied these two primer sets to DNA samples isolated from individuals with trisomy 21 (n = 36); trisomy 18 (n = 6); trisomy 13 (n = 4); 45, X (n = 5); 47, XXX (n = 3); 48, XXYY (n = 2); and unaffected controls (n = 40). We evaluated the performance of this method using the karyotyping results. A correct and unambiguous diagnosis with 100% sensitivity and 100% specificity, was achieved for clinical samples examined. Thus, the present study demonstrates that SD-QF-PCR is a robust, rapid and sensitive method for the diagnosis of common aneuploidies, and these analyses can be performed in less than 4 hours for a single sample, providing a competitive alternative for routine use.
PMCID: PMC3953018  PMID: 24625828
3.  Obstruction of Dengue Virus Maturation by Fab Fragments of the 2H2 Antibody 
Journal of Virology  2013;87(16):8909-8915.
The 2H2 monoclonal antibody recognizes the precursor peptide on immature dengue virus and might therefore be a useful tool for investigating the conformational change that occurs when the immature virus enters an acidic environment. During dengue virus maturation, spiky, immature, noninfectious virions change their structure to form smooth-surfaced particles in the slightly acidic environment of the trans-Golgi network, thereby allowing cellular furin to cleave the precursor-membrane proteins. The dengue virions become fully infectious when they release the cleaved precursor peptide upon reaching the neutral-pH environment of the extracellular space. Here we report on the cryo-electron microscopy structures of the immature virus complexed with the 2H2 antigen binding fragments (Fab) at different concentrations and under various pH conditions. At neutral pH and a high concentration of Fab molecules, three Fab molecules bind to three precursor-membrane proteins on each spike of the immature virus. However, at a low concentration of Fab molecules and pH 7.0, only two Fab molecules bind to each spike. Changing to a slightly acidic pH caused no detectable change of structure for the sample with a high Fab concentration but caused severe structural damage to the low-concentration sample. Therefore, the 2H2 Fab inhibits the maturation process of immature dengue virus when Fab molecules are present at a high concentration, because the three Fab molecules on each spike hold the precursor-membrane molecules together, thereby inhibiting the normal conformational change that occurs during maturation.
PMCID: PMC3754034  PMID: 23740974
4.  Protective effect of senegenin on splenectomy-induced postoperative cognitive dysfunction in elderly rats 
Postoperative cognitive dysfunction (POCD) is common in elderly patients. Senegenin, an active component of extracts from Polygala tenuifolia root, a traditional Chinese medicine, has neuroprotective and neuroregenerative effects. However, the mechanism underlying the effects of senegenin against postoperative cognitive impairment in elderly individuals has yet to be elucidated. The aim of this study was to investigate the protective effects of senegenin on the cognitive functions of elderly rats with splenectomy-induced POCD. Results from a Morris water maze test suggested that splenectomy induced a transient cognitive deficiency in the elderly rats; however, when the rats were treated with senegenin, the cognitive impairment was notably attenuated. Further experiments showed that senegenin significantly inhibited the mRNA and protein expression of several key pro-inflammatory cytokines, specifically, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6 and IL-8, in the hippocampal tissues of elderly rats following splenectomy. In order to investigate the molecular mechanism involved, the expression and activity of the Toll-like receptor 4 (TLR4) signaling pathway was assessed. On day 1 postoperatively, it was observed that senegenin markedly suppressed the mRNA and protein expression of TLR4, myeloid differentiation factor 88 (MyD88) and TIR domain-containing adaptor-inducing interferon-β (TRIF). Furthermore, the phosphorylation levels of nuclear factor-κB (NF-κB) p65 and inhibitor of NF-κB (IκBα) were also decreased following senegenin treatment on the first day subsequent to surgery. These results suggest that senegenin suppressed splenectomy-induced transient cognitive impairment in elderly rats, possibly by downregulating two signaling pathways involved in inflammation, TLR4/MyD88/NF-κB and TLR4/TRIF/NF-κB, to further inhibit the expression of key pro-inflammatory cytokines, specifically, TNF-α, IL-1β, IL-6 and IL-8, and ultimately the neuroinflammation in the hippocampal tissues. In conclusion, the present study revealed that senegenin exhibited neuroprotective effects against splenectomy-induced transient cognitive impairment in elderly rats, which indicated that senegenin may be a promising agent for the treatment of POCD.
PMCID: PMC3961123  PMID: 24660030
postoperative cognitive dysfunction; senegenin; elderly; pro-inflammatory cytokines; signaling pathways
5.  Elevated Peripheral Frequencies of Th22 Cells: A Novel Potent Participant in Obesity and Type 2 Diabetes 
PLoS ONE  2014;9(1):e85770.
Chronic low-grade inflammation has long been recognized as the central link between obesity and type 2 diabetes (T2D). The novel subset of T helper (Th) cells, Th22, plays an emerging role in chronic inflammation. We investigated the potential association between Th22 and the pathogenesis of obesity and T2D.
Ninety T2D inpatients (T2D group), 30 healthy participants with BMI ranged from 19 to 23.9 kg/m2 (CTL group) and 30 metabolically healthy obese controls with BMI ≥ 30 kg/m2 (MHO group) were employed in our study. Peripheral frequencies of Th22 and Th1 and Th17 cells were determined by flow cytometry based on their specific cytokine patterns. Cytokine levels in fresh plasma were quantified by ELISA.
Compared to that in CTL group (1.18±0.06%, n = 28), peripheral frequency of Th22 cells was significantly increased in MHO group (1.88±0.10%, n = 30) and in T2D group (2.247±0.10%, n = 89). There was a consistent notable increase in plasma interleukin (IL)-22 of T2D patients [47.56 (30.55–76.89) pg/mL] as compared with that of MHO group [36.65 (29.52–55.70) pg/ml; *P<0.0001] and CTLs [36.33 (31.93–40.62) pg/mL; *P<0.0001]. Furthermore, other than Th1/Th17, previously frequently described participants in obesity and T2D, there was a strong correlation between Th22 frequency and the homeostasis model of assessment for insulin resistance index (r = 0.6771, *P<0.0001) and HOMA for β-cell function (r = −0.7264, *P<0.0001).
There were increased Th22 frequencies and IL-22 levels in obesity and T2D. Elevated Th22 and IL-22 also aided in the differentiation of MHO from T2D patients. The notable correlation implied that Th22 might play a more determinant role in both insulin resistance and β-cell impairment.
PMCID: PMC3894984  PMID: 24465695
6.  RfaH Suppresses Small RNA MicA Inhibition of fimB Expression in Escherichia coli K-12 
Journal of Bacteriology  2014;196(1):148-156.
The phase variation (reversible on-off switching) of the type 1 fimbrial adhesin of Escherichia coli involves a DNA inversion catalyzed by FimB (switching in either direction) or FimE (on-to-off switching). Here, we demonstrate that RfaH activates expression of a FimB-LacZ protein fusion while having a modest inhibitory effect on a comparable fimB-lacZ operon construct and on a FimE-LacZ protein fusion, indicating that RfaH selectively controls fimB expression at the posttranscriptional level. Further work demonstrates that loss of RfaH enables small RNA (sRNA) MicA inhibition of fimB expression even in the absence of exogenous inducing stress. This effect is explained by induction of σE, and hence MicA, in the absence of RfaH. Additional work confirms that the procaine-dependent induction of micA requires OmpR, as reported previously (A. Coornaert et al., Mol. Microbiol. 76:467–479, 2010, doi:10.1111/j.1365-2958.2010.07115.x), but also demonstrates that RfaH inhibition of fimB transcription is enhanced by procaine independently of OmpR. While the effect of procaine on fimB transcription is shown to be independent of RcsB, it was found to require SlyA, another known regulator of fimB transcription. These results demonstrate a complex role for RfaH as a regulator of fimB expression.
PMCID: PMC3911127  PMID: 24163336
7.  High dose of extracellular ATP switched autophagy to apoptosis in anchorage-dependent and anchorage-independent hepatoma cells 
Purinergic Signalling  2013;9(4):585-598.
Extracellular adenosine triphosphate (eATP) transduces purinergic signal and plays an important regulatory role in many biological processes, including tumor cell growth and cell death. A large amount of eATP exists in the fast-growing tumor center and inflammatory tumor microenvironment. Tumor cells could acquire anoikis resistance and anchorage independence in tumor microenvironment and further cause metastatic lesion. Whether such a high amount of eATP has any effect on the anchored and non-anchored tumor cells in tumor microenvironment has not been elucidated and is investigated in this study. Our data showed that autophagy helped hepatoma cells to maintain survival under the treatment of no more than 1 mM of eATP. Only when eATP concentration reached a relatively high level (2.5 mM), cell organelle could not be further maintained by autophagy, and apoptosis and cell death occurred. In hepatoma cells under treatment of 2.5 mM of eATP, an AMP-activated protein kinase (AMPK) pathway was dramatically activated while mTOR signaling pathway was suppressed in coordination with apoptosis. Further investigation showed that the AMPK/mTOR axis played a key role in tipping the balance between autophagy-mediated cell survival and apoptosis-induced cell death under the treatment of eATP. This work provides evidence to explain how hepatoma cells escape from eATP-induced cytotoxicity as well as offers an important clue to consider effective manipulation of cancer.
PMCID: PMC3889388  PMID: 23780311
Apoptosis; Autophagy; Anoikis; Extracellular ATP; AMPK; mTOR
8.  Improved Early Postresuscitation EEG Activity for Animals Treated with Hypothermia Predicted 96 hr Neurological Outcome and Survival in a Rat Model of Cardiac Arrest 
BioMed Research International  2013;2013:312137.
Purpose. To investigate the effect of hypothermia on 96 hr neurological outcome and survival by quantitatively characterizing early postresuscitation EEG in a rat model of cardiac arrest. Materials and Methods. In twenty male Sprague-Dawley rats, cardiac arrest was induced through high frequency transesophageal cardiac pacing. Cardiopulmonary resuscitation was initiated after 5 mins untreated arrest. Immediately after resuscitation, animals were randomized to either 2 hrs of hypothermia (N = 10) or normothermia (N = 10). EEG, ECG, aortic pressure, and core temperature were continuously recorded for 6 hrs. Neurological outcome was evaluated daily during the 96 hrs postresuscitation period. Results. No differences in the baseline measurements and resuscitation outcome were observed between groups. However, 96 hr neurological deficit score (204 ± 255 versus 500 ± 0, P = 0.005) and survival (6/10 versus 0/10, P = 0.011) were significantly better in the hypothermic group. Quantitative analysis of early postresuscitation EEG revealed that burst frequency and spectrum entropy were greatly improved in the hypothermic group and correlated with 96 hr neurological outcome and survival. Conclusion. The improved burst frequency during burst suppression period and preserved spectrum entropy after restoration of continuous background EEG activity for animals treated with hypothermia predicted favorable neurological outcome and survival in this rat model of cardiac arrest.
PMCID: PMC3867829  PMID: 24369012
9.  Tyrosine 132 Phosphorylation of Influenza A Virus M1 Protein Is Crucial for Virus Replication by Controlling the Nuclear Import of M1 
Journal of Virology  2013;87(11):6182-6191.
Phosphorylation of viral proteins plays important roles in the influenza A virus (IAV) life cycle. By using mass spectrometry, we identified tyrosine 132 (Y132) as a phosphorylation site of the matrix protein (M1) of the influenza virus A/WSN/1933(H1N1). Phosphorylation at this site is essential to the process of virus replication by controlling the nuclear import of M1. We further demonstrated that the phosphorylated tyrosine is crucial for the binding of M1 to the nuclear import factor importin-α1, since any substitutions at this site severely reduce this protein-protein interaction and damage the importin-α1-mediated nuclear import of M1. Additionally, the tyrosine phosphorylation which leads to the nuclear import of M1 is blocked by a Janus kinase inhibitor. The present study reveals a pivotal role of this tyrosine phosphorylation in the intracellular transportation of M1, which controls the process of viral replication.
PMCID: PMC3648105  PMID: 23536660
10.  Anti-Inflammatory Activity of Water-Soluble Polysaccharide of Agaricus blazei Murill on Ovariectomized Osteopenic Rats 
In the present study, we investigated the anti-inflammatory activity of water-soluble polysaccharide of Agaricus blazei Murill (WSP-AbM) on ovariectomized osteopenic rats. The rats were administered orally WSP-AbM (200 mg/kg BW) for 8 weeks. Subsequent serum maleic dialdehyde (MDA) level, total antioxidant status (TAOS), nuclear factor kappa B (NF-κB) level, polymorphonuclear (PMN) cells level, interleukin-1β (IL-1β) level, inducible nitric oxide synthase (iNOS) level, tumor necrosis factor-α (TNF-α) level, adhesion molecule (ICAM-1), and cyclooxygenase-2 (COX-2) were determined by enzyme linked immunosorbent assay (ELISA) and immunohistochemistry, respectively. WSP-AbM administration markedly (P < 0.05) decreased serum IL-1β and TNF-α levels and the expressions of ICAM-1, COX-2, and iNOS NF-κB compared with OVX rats. WSP-AbM administration alsomarkedly (P < 0.05) decreased PMN infiltration. In conclusion, we observed that WSP-AbM supplementation had anti-inflammatory effects in a model of osteoporosis disease.
PMCID: PMC3857733  PMID: 24348690
11.  Gene-based multiple regression association testing for combined examination of common and low frequency variants in quantitative trait analysis 
Frontiers in Genetics  2013;4:233.
Multi-marker methods for genetic association analysis can be performed for common and low frequency SNPs to improve power. Regression models are an intuitive way to formulate multi-marker tests. In previous studies we evaluated regression-based multi-marker tests for common SNPs, and through identification of bins consisting of correlated SNPs, developed a multi-bin linear combination (MLC) test that is a compromise between a 1 df linear combination test and a multi-df global test. Bins of SNPs in high linkage disequilibrium (LD) are identified, and a linear combination of individual SNP statistics is constructed within each bin. Then association with the phenotype is represented by an overall statistic with df as many or few as the number of bins. In this report we evaluate multi-marker tests for SNPs that occur at low frequencies. There are many linear and quadratic multi-marker tests that are suitable for common or low frequency variant analysis. We compared the performance of the MLC tests with various linear and quadratic statistics in joint or marginal regressions. For these comparisons, we performed a simulation study of genotypes and quantitative traits for 85 genes with many low frequency SNPs based on HapMap Phase III. We compared the tests using (1) set of all SNPs in a gene, (2) set of common SNPs in a gene (MAF ≥ 5%), (3) set of low frequency SNPs (1% ≤ MAF < 5%). For different trait models based on low frequency causal SNPs, we found that combined analysis using all SNPs including common and low frequency SNPs is a good and robust choice whereas using common SNPs alone or low frequency SNP alone can lose power. MLC tests performed well in combined analysis except where two low frequency causal SNPs with opposing effects are positively correlated. Overall, across different sets of analysis, the joint regression Wald test showed consistently good performance whereas other statistics including the ones based on marginal regression had lower power for some situations.
PMCID: PMC3824159  PMID: 24273553
genetic association analysis; multi-marker association analysis; rare variant analysis; common variant analysis; multi-bin multi-marker tests; generalized Wald test; minimum p-value test; indirect association
12.  Efficacy and Safety of Endovascular Treatment versus Intravenous Thrombolysis for Acute Ischemic Stroke: A Meta-Analysis of Randomized Controlled Trials 
PLoS ONE  2013;8(10):e77849.
Background and Purpose
Although endovascular therapy (ET) is increasingly used in patients with moderate to severe acute ischemic stroke, its efficacy and safety remains controversial. We performed a meta-analysis aiming to compare the benefits and safety of endovascular treatment and intravenous thrombolysis in the treatment of acute ischemic stroke.
We systematically searched PubMed, Embase, Science direct and Springer unitil July, 2013. The primary outcomes included good outcome (mRS ≤ 2) and excellent outcome (mRS ≤ 1) at 90 days or at trial end point. Secondary outcomes were occurrence of symptomatic hemorrhage and all-cause mortality.
Using a prespecified search strategy, 5 RCTs with 1106 patients comparing ET and intravenous thrombolysis (IVT) were included in the meta-analysis. ET and IVT were associated with similar good (43.06% vs 41.78%; OR=1.14; 95% CI, 0.77 to 1.69; P=0.52;) and excellent (30.43% vs 30.42%; OR=1.05; 95% CI, 0.80 to 1.38; P=0.72;) outcome. For additional end points, ET was not associated with increased occurrence of symptomatic hemorrhage (6.25% vs. 6.22%; OR=1.03; 95% CI, 0.62 to 1.69; P=0.91;), or all-cause mortality (18.45% vs. 17.35%; OR=1.00; 95% CI, 0.73 to 1.39; P=0.99;).
Formal meta-analysis indicates that there are similar safety outcomes and functional independence with endovascular therapy and intravenous thrombolysis for acute ischemic stroke.
PMCID: PMC3814965  PMID: 24204995
13.  Turning WAT into BAT: a review on regulators controlling the browning of white adipocytes 
Bioscience Reports  2013;33(5):e00065.
Adipose tissue has a central role in the regulation of energy balance and homoeostasis. There are two main types of adipose tissue: WAT (white adipose tissue) and BAT (brown adipose tissue). WAT from certain depots, in response to appropriate stimuli, can undergo a process known as browning where it takes on characteristics of BAT, notably the induction of UCP1 (uncoupling protein 1) expression and the presence of multilocular lipid droplets and multiple mitochondria. How browning is regulated is an intense topic of investigation as it has the potential to tilt the energy balance from storage to expenditure, a strategy that holds promise to combat the growing epidemic of obesity and metabolic syndrome. This review focuses on the transcriptional regulators as well as various proteins and secreted mediators that have been shown to play a role in browning. Emphasis is on describing how many of these factors exert their effects by regulating the three main transcriptional regulators of classical BAT development, namely PRDM16 (PR domain containing 16), PPARγ (peroxisome proliferator-activated receptor γ) and PGC-1α (peroxisome proliferator-activated receptor γ coactivator 1α), which have been shown to be the key nodes in the regulation of inducible brown fat.
PMCID: PMC3764508  PMID: 23895241
beige fat; browning; peroxisome-proliferator-activated receptor γ (PPARγ); peroxisome-proliferator-activated receptor γ coactivator 1-α (PGC-1α); PR domain containing 16 (PRDM16); white adipocytes; 4E-BP1, eukaryotic translation initiation factor 4E binding protein 1; ANP, atrial natriuretic peptide; ATF2, activating transcription factor 2; BAT, brown adipose tissue; BMP7, bone morphogenetic protein 7; C/EBP, CCAAT/enhancer-binding protein; Cidea, cell death-inducing DFFA-like effector a; CNP, cardiac natriuretic peptide; COX2, cyclo-oxygenase 2; CtBP, C-terminal-binding protein; EBF2, early B cell factor-2; eIF4E, eukaryotic translation initiation factor 4E; Elovl3, elongation of very long chain fatty acids (FEN1/Elo2, SUR4/Elo3, yeast)-like 3; FGF21, fibroblast growth factor 21; FoxC2, forkhead box protein C2; MAPK, mitogen-activated protein kinase; miRNA, microRNA; Myf5, myogenic factor 5; NPRC, natriuretic peptide receptor C; PGC-1α, peroxisome-proliferator-activated receptor γ coactivator 1α; PGI2, prostacyclin; PKA, protein kinase A (=cAMP-dependent protein kinase); PKG, protein kinase G (=cGMP-dependent protein kinase); PPARγ, peroxisome-proliferator-activated receptor gamma; PRDM16, PR domain containing 16; pRb, retinoblastoma protein; SRC-1, steroid receptor coactivator-1; SVF, stromal vascular fraction; TBX15, T-box 15; TFAM, mitochondrial transcription factor A; TIF2, transcriptional intermediary factor-2; TRPV4, transient receptor potential vanilloid 4; UCP1, uncoupling protein 1; WAT, white adipose tissue
14.  An Open System for Intravascular Ultrasound Imaging 
Visualization of the blood vessels can provide valuable morphological information for diagnosis and therapy strategies for cardiovascular disease. Intravascular ultrasound (IVUS) is able to delineate internal structures of vessel wall with fine spatial resolution. However, the developed IVUS is insufficient to identify the fibrous cap thickness and tissue composition of atherosclerotic lesions. Novel imaging strategies have been proposed, such as increasing the center frequency of ultrasound or using a modulated excitation technique to improve the accuracy of diagnosis. Dual-mode tomography combining IVUS with optical tomography has also been developed to determine tissue morphology and characteristics. The implementation of these new imaging methods requires an open system that allows users to customize the system for various studies. This paper presents the development of an IVUS system that has open structures to support various imaging strategies. The system design is based on electronic components and printed circuit board, and provides reconfigurable hardware implementation, programmable image processing algorithms, flexible imaging control, and raw RF data acquisition. In addition, the proposed IVUS system utilized a miniaturized ultrasound transducer constructed using PMN-PT single crystal for better piezoelectric constant and electromechanical coupling coefficient than traditional lead zirconate titanate (PZT) ceramics. Testing results showed that the IVUS system could offer a minimum detectable signal of 25 μV, allowing a 51 dB dynamic range at 47 dB gain, with a frequency range from 20 to 80 MHz. Finally, phantom imaging, in vitro IVUS vessel imaging, and multimodality imaging with photoacoustics were conducted to demonstrate the performance of the open system.
PMCID: PMC3760234  PMID: 23143570
15.  Reduction of Ribosome Level Triggers Flocculation of Fission Yeast Cells 
Eukaryotic Cell  2013;12(3):450-459.
Deletion of ribosomal protein L32 genes resulted in a nonsexual flocculation of fission yeast. Nonsexual flocculation also occurred when two other ribosomal protein genes, rpl21-2 and rpl9-2, were deleted. However, deletion of two nonribosomal protein genes, mpg and fbp, did not cause flocculation. Overall transcript levels of rpl32 in rpl32-1Δ and rpl32-2Δ cells were reduced by 35.9% and 46.9%, respectively, and overall ribosome levels in rpl32-1Δ and rpl32-2Δ cells dropped 31.1% and 27.8%, respectively, compared to wild-type cells. Interestingly, ribosome protein expression levels and ribosome levels were also reduced greatly in sexually flocculating diploid YHL6381/WT (h+/h−) cells compared to a mixture of YHL6381 (h+) and WT (h−) nonflocculating haploid cells. Transcriptome analysis indicated that the reduction of ribosomal levels in sexual flocculating cells was caused by more-extensive suppression of ribosomal biosynthesis gene expression, while the reduction of ribosomal levels caused by deleting ribosomal protein genes in nonsexual flocculating cells was due to an imbalance between ribosomal proteins. We propose that once the reduction of ribosomal levels is below a certain threshold value, flocculation is triggered.
PMCID: PMC3629774  PMID: 23355005
16.  Influence of fiber posts on the fracture resistance of endodontically treated premolars with different dental defects 
This study aimed to evaluate the influence of quartz fiber post placement on the fracture resistance of endodontically treated premolars with different dental defects under dynamic loading. Fifty extracted single-rooted mandibular premolars were randomized into five groups. Each group was prepared according to numbers of residual walls ranged from 0 to 4. Then each group was divided into two subgroups with one restored with quartz fiber posts and the other without posts. In no-post groups, gutta percha point 2 mm below cemento-enamel junction was removed. Composite resin was adapted to the well and used to shape the core directly. Each tooth was restored with a complete metal crown. Dynamic loading was carried out in a masticatory simulator with a nominal load of 50 N at 2 Hz for 300 000 loading cycles. Then a quasi-statically load was applied in a universal testing machine 30° to the long axis with a crosshead speed of 1 mm⋅min−1 until fracture. Data were analyzed with one-way analysis of variance and pairwise comparison (P<0.05). No specimens failed during dynamic loading. The fracture resistance enhanced with the increase of numbers of coronal walls and the differences were significant (P<0.05). Placement of fiber posts had a significant effect when fewer than two walls remained (P<0.05), but it had no significant influence in groups with two, three or four walls (P>0.05). Fiber post did not change failure mode, and the fracture pattern was mainly favorable. More dentin walls need to be retained in clinic. When no less than two walls remained, a fiber post is not always necessary.
PMCID: PMC3967333  PMID: 23907677
dynamic loading; fiber post; fracture resistance; residual wall
17.  Ultrasound Bio-Microscopic Image Segmentation for Evaluation of Zebrafish Cardiac Function 
Zebrafish can fully regenerate their myocardium after ventricular resection without evidence of scars. This extraordinary regenerative ability provides an excellent model system to study the activation of the regenerative potential for human heart tissue. In addition to the morphology, it is vital to understand the cardiac function of zebrafish. To characterize adult zebrafish cardiac function, an ultrasound biomicroscope (UBM) was customized for real-time imaging of the zebrafish heart (about 1 mm in diameter) at a resolution of around 37 µm. Moreover, we developed an image segmentation algorithm to track the cardiac boundary and measure the dynamic size of the zebrafish heart for further quantification of zebrafish cardiac function. The effectiveness and accuracy of the proposed segmentation algorithm were verified on a tissue-mimicking phantom and in vivo zebrafish echocardiography. The quantitative evaluation demonstrated that the accuracy of the proposed algorithm is comparable to the manual delineation by experts.
PMCID: PMC3750995  PMID: 23549532
18.  A Flexible Annular-Array Imaging Platform for Micro-Ultrasound 
Micro-ultrasound is an invaluable imaging tool for many clinical and preclinical applications requiring high resolution (approximately several tens of micrometers). Imaging systems for micro-ultrasound, including single-element imaging systems and linear-array imaging systems, have been developed extensively in recent years. Single-element systems are cheaper, but linear-array systems give much better image quality at a higher expense. Annular-array-based systems provide a third alternative, striking a balance between image quality and expense. This paper presents the development of a novel programmable and real-time annular-array imaging platform for micro-ultrasound. It supports multi-channel dynamic beamforming techniques for large-depth-of-field imaging. The major image processing algorithms were achieved by a novel field-programmable gate array technology for high speed and flexibility. Real-time imaging was achieved by fast processing algorithms and high-speed data transfer interface. The platform utilizes a printed circuit board scheme incorporating state-of-the-art electronics for compactness and cost effectiveness. Extensive tests including hardware, algorithms, wire phantom, and tissue mimicking phantom measurements were conducted to demonstrate good performance of the platform. The calculated contrast-to-noise ratio (CNR) of the tissue phantom measurements were higher than 1.2 in the range of 3.8 to 8.7 mm imaging depth. The platform supported more than 25 images per second for real-time image acquisition. The depth-of-field had about 2.5-fold improvement compared to single-element transducer imaging.
PMCID: PMC3738186  PMID: 23287923
19.  Re-Ranking Sequencing Variants in the Post-GWAS Era for Accurate Causal Variant Identification 
PLoS Genetics  2013;9(8):e1003609.
Next generation sequencing has dramatically increased our ability to localize disease-causing variants by providing base-pair level information at costs increasingly feasible for the large sample sizes required to detect complex-trait associations. Yet, identification of causal variants within an established region of association remains a challenge. Counter-intuitively, certain factors that increase power to detect an associated region can decrease power to localize the causal variant. First, combining GWAS with imputation or low coverage sequencing to achieve the large sample sizes required for high power can have the unintended effect of producing differential genotyping error among SNPs. This tends to bias the relative evidence for association toward better genotyped SNPs. Second, re-use of GWAS data for fine-mapping exploits previous findings to ensure genome-wide significance in GWAS-associated regions. However, using GWAS findings to inform fine-mapping analysis can bias evidence away from the causal SNP toward the tag SNP and SNPs in high LD with the tag. Together these factors can reduce power to localize the causal SNP by more than half. Other strategies commonly employed to increase power to detect association, namely increasing sample size and using higher density genotyping arrays, can, in certain common scenarios, actually exacerbate these effects and further decrease power to localize causal variants. We develop a re-ranking procedure that accounts for these adverse effects and substantially improves the accuracy of causal SNP identification, often doubling the probability that the causal SNP is top-ranked. Application to the NCI BPC3 aggressive prostate cancer GWAS with imputation meta-analysis identified a new top SNP at 2 of 3 associated loci and several additional possible causal SNPs at these loci that may have otherwise been overlooked. This method is simple to implement using R scripts provided on the author's website.
Author Summary
As next-generation sequencing (NGS) costs continue to fall and genome-wide association study (GWAS) platform coverage improves, the human genetics community is positioned to identify potentially causal variants. However, current NGS or imputation-based studies of either the whole genome or regions previously identified by GWAS have not yet been very successful in identifying causal variants. A major hurdle is the development of methods to distinguish disease-causing variants from their highly-correlated proxies within an associated region. We show that various common factors, such as differential sequencing or imputation accuracy rates and linkage disequilibrium patterns, with or without GWAS-informed region selection, can substantially decrease the probability of identifying the correct causal SNP, often by more than half. We then describe a novel and easy-to-implement re-ranking procedure that can double the probability that the causal SNP is top-ranked in many settings. Application to the NCI Breast and Prostate Cancer (BPC3) Cohort Consortium aggressive prostate cancer data identified new top SNPs within two associated loci previously established via GWAS, as well as several additional possible causal SNPs that had been previously overlooked.
PMCID: PMC3738448  PMID: 23950724
20.  Systematic Analysis of the Functions of Lysine Acetylation in the Regulation of Tat Activity 
PLoS ONE  2013;8(6):e67186.
The Tat protein of HIV-1 has several well-known properties, such as nucleocytoplasmic trafficking, transactivation of transcription, interaction with tubulin, regulation of mitotic progression, and induction of apoptosis. Previous studies have identified a couple of lysine residues in Tat that are essential for its functions. In order to analyze the functions of all the lysine residues in Tat, we mutated them individually to alanine, glutamine, and arginine. Through systematic analysis of the lysine mutants, we discovered several previously unidentified characteristics of Tat. We found that lysine acetylation could modulate the subcellular localization of Tat, in addition to the regulation of its transactivation activity. Our data also revealed that lysine mutations had distinct effects on microtubule assembly and Tat binding to bromodomain proteins. By correlation analysis, we further found that the effects of Tat on apoptosis and mitotic progression were not entirely attributed to its effect on microtubule assembly. Our findings suggest that Tat may regulate diverse cellular activities through binding to different proteins and that the acetylation of distinct lysine residues in Tat may modulate its interaction with various partners.
PMCID: PMC3695041  PMID: 23826228
21.  Nutrition and the Risk of Alzheimer's Disease 
BioMed Research International  2013;2013:524820.
Alzheimer's disease (AD) is a progressive neurodegenerative disorder that accounts for the major cause of dementia, and the increasing worldwide prevalence of AD is a major public health concern. Increasing epidemiological studies suggest that diet and nutrition might be important modifiable risk factors for AD. Dietary supplementation of antioxidants, B vitamins, polyphenols, and polyunsaturated fatty acids are beneficial to AD, and consumptions of fish, fruits, vegetables, coffee, and light-to-moderate alcohol reduce the risk of AD. However, many of the results from randomized controlled trials are contradictory to that of epidemiological studies. Dietary patterns summarizing an overall diet are gaining momentum in recent years. Adherence to a healthy diet, the Japanese diet, and the Mediterranean diet is associated with a lower risk of AD. This paper will focus on the evidence linking many nutrients, foods, and dietary patterns to AD.
PMCID: PMC3705810  PMID: 23865055
22.  Clinical Implications and Molecular Mechanisms of Immunoparalysis Following Cardiopulmonary Bypass 
We used a whole blood assay to characterize the immune system’s response following cardiopulmonary bypass (CPB) in children to identify the risk for postoperative infections. We assessed the impact of CPB on histone methylation as a potential mechanism for altering gene expression necessary for the immune system’s capacity to defend against infections.
We prospectively enrolled patients <18 years old undergoing heart surgery requiring CPB at C.S. Mott Children’s Hospital. Blood was obtained from patients prior to CPB, on CPB and on postoperative days 1, 3 and 5. Ex vivo LPS-induced TNF-α production measured the capacity of the immune system. Serum cytokines were measured using a multiplex assay. Chromatin Immunoprecipitation (ChIP) to detect histone modifications at the interleukin (IL)-10 promoter was performed on circulating mononuclear cells from a subgroup of patients.
We enrolled 92 patients and postoperative day 1 samples identified a subpopulation of immunocompetent patients at low risk for infections with a specificity of 93% (C.I. 83–98%) and a negative predictive value of 88% (C.I. 77–95%; p=0.006). Patients classified as immunoparalyzed had serum IL-10 levels 2.4 fold higher than the immunocompetent group (mean 14.3 ± 18.3 pg/ml vs. 6.0 ± 5.0 pg/ml, p=0.01). In a subgroup of patients, we identified a greater percent of the “gene on” epigenetic signature, H3K4me3, associated with the IL-10 promoter following CPB.
Our data demonstrate that immunophenotyping patients after CPB can predict their risk of developing postoperative infections. Novel mechanistic data suggest that CPB impacts epigenetic alterations in IL-10 gene regulation.
PMCID: PMC3262077  PMID: 21996297
Cardiopulmonary Bypass; Immunoparalysis; Post-translational histone modification; Interleukin-10; Epigenetics; Sepsis
23.  Homeobox C9 Is Not Potentially Related to Congenital Heart Disease in Chinese Patients 
Background: Congenital heart disease (CHD) is one of the most common human birth defects. The etiology and pathogenesis of CHD are complex and involve several genes as well as multiple changes in signaling pathways. The aim of this study was to identify potential pathological mutations in the Homeobox C9 (Hoxc9) gene in 350 Chinese children with CHD to further understand the etiology of CHD. Method: Sequence analysis of the Hoxc9 gene in 350 nonsyndromic patients with CHD Result: We did not identify any nonsynonymous variants in the coding regions of Hoxc9 in the patients with CHD. We found one synonymous variant c.C564T (p. his188his) in one ventricular septal defect patient. We also identified four previously reported polymorphisms (rs56368105, rs12817092, rs34079606, and rs2241820) in CHD. Conclusions: We did not find any diagnostic alterations in the coding regions of Hoxc9 among the patients with CHD. Nevertheless, to our knowledge, this is the first study of Hoxc9 in nonsyndromic CHD and has expanded our overall knowledge of the etiology of this disease.
PMCID: PMC3354584  PMID: 22106857
24.  A knock-in model of human epilepsy in Drosophila reveals a novel cellular mechanism associated with heat-induced seizure 
Over 40 missense mutations in the human SCN1A sodium channel gene are linked to an epilepsy syndrome termed genetic epilepsy with febrile seizures plus (GEFS+). Inheritance of GEFS+ is dominant but the underlying cellular mechanisms remain poorly understood. Here we report knock-in of a GEFS+ SCN1A mutation (K1270T) into the Drosophila sodium channel gene, para, causes a semi-dominant temperature-induced seizure phenotype. Electrophysiological studies of GABAergic interneurons in the brains of adult GEFS+ flies reveal a novel cellular mechanism underlying heat-induced seizures: the deactivation threshold for persistent sodium currents reversibly shifts to a more negative voltage when the temperature is elevated. This leads to sustained depolarizations in GABAergic neurons and reduced inhibitory activity in the central nervous system. Further, our data indicate a natural temperature-dependent shift in sodium current deactivation (exacerbated by mutation) may contribute to febrile seizures in GEFS+ and perhaps normal individuals.
PMCID: PMC3482260  PMID: 23055484
25.  Paralogous Ribosomal Protein L32-1 and L32-2 in Fission Yeast May Function Distinctively in Cellular Proliferation and Quiescence by Changing the Ratio of Rpl32 Paralogs 
PLoS ONE  2013;8(4):e60689.
Fission yeast cells express Rpl32-2 highly while Rpl32-1 lowly in log phase; in contrast, expression of Rpl32-1 raises and reaches a peak level while Rpl32-2 is downregulated to a low basic level when cells enter into stationary phase. Overexpression of Rpl32-1 inhibits cell growth while overexpression of Rpl32-2 does not. Deleting rpl32-2 impairs cell growth more severely than deleting rpl32-1 does. Cell growth impaired by deleting either paralog can be rescued completely by reintroducing rpl32-2, but only partly by rpl32-1. Overexpression of Rpl32-1 inhibits cell division, yielding 4c DNA and multiple septa, while overexpressed Rpl32-2 promotes it. Transcriptomics analysis proved that Rpl32 paralogs regulate expression of a subset of genes related with cell division and stress response in a distinctive way. This functional difference of the two paralogs is due to their difference of 95th amino acid residue. The significance of a competitive inhibition between Rpl32 paralogs on their expression is discussed.
PMCID: PMC3618328  PMID: 23577148

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