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1.  Transcriptome Profiling and Physiological Studies Reveal a Major Role for Aromatic Amino Acids in Mercury Stress Tolerance in Rice Seedlings 
PLoS ONE  2014;9(5):e95163.
Mercury (Hg) is a serious environmental pollution threat to the planet. The accumulation of Hg in plants disrupts many cellular-level functions and inhibits growth and development, but the mechanism is not fully understood. To gain more insight into the cellular response to Hg, we performed a large-scale analysis of the rice transcriptome during Hg stress. Genes induced with short-term exposure represented functional categories of cell-wall formation, chemical detoxification, secondary metabolism, signal transduction and abiotic stress response. Moreover, Hg stress upregulated several genes involved in aromatic amino acids (Phe and Trp) and increased the level of free Phe and Trp content. Exogenous application of Phe and Trp to rice roots enhanced tolerance to Hg and effectively reduced Hg-induced production of reactive oxygen species. Hg induced calcium accumulation and activated mitogen-activated protein kinase. Further characterization of the Hg-responsive genes we identified may be helpful for better understanding the mechanisms of Hg in plants.
PMCID: PMC4026224  PMID: 24840062
2.  Streptomyces coelicolor Encodes a Urate-Responsive Transcriptional Regulator with Homology to PecS from Plant Pathogens 
Journal of Bacteriology  2013;195(21):4954-4965.
Many transcriptional regulators control gene activity by responding to specific ligands. Members of the multiple-antibiotic resistance regulator (MarR) family of transcriptional regulators feature prominently in this regard, and they frequently function as repressors in the absence of their cognate ligands. Plant pathogens such as Dickeya dadantii encode a MarR homolog named PecS that controls expression of a gene encoding the efflux pump PecM in addition to other virulence genes. We report here that the soil bacterium Streptomyces coelicolor also encodes a PecS homolog (SCO2647) that regulates a pecM gene (SCO2646). S. coelicolor PecS, which exists as a homodimer, binds the intergenic region between pecS and pecM genes with high affinity. Several potential PecS binding sites were found in this intergenic region. The binding of PecS to its target DNA can be efficiently attenuated by the ligand urate, which also quenches the intrinsic fluorescence of PecS, indicating a direct interaction between urate and PecS. In vivo measurement of gene expression showed that activity of pecS and pecM genes is significantly elevated after exposure of S. coelicolor cultures to urate. These results indicate that S. coelicolor PecS responds to the ligand urate by attenuated DNA binding in vitro and upregulation of gene activity in vivo. Since production of urate is associated with generation of reactive oxygen species by xanthine dehydrogenase, we propose that PecS functions under conditions of oxidative stress.
PMCID: PMC3807492  PMID: 23995633
3.  Label-free blood plasma test based on surface-enhanced Raman scattering for tumor stages detection in nasopharyngeal cancer 
Scientific Reports  2014;4:4751.
This study aims to evaluate the feasibility of a label-free nanobiosensor based on blood plasma surface-enhanced Raman spectroscopy (SERS) method for exploring variability of different tumor (T) stages in nasopharyngeal cancer (NPC). Au nanoparticles as the SERS-active nanostructures were directly mixed with human blood plasma to enhance the Raman scattering signals. High quality SERS spectra can be acquired from blood plasma samples belong to 60 healthy volunteers, 25 NPC patients with T1 stage and 75 NPC patients with T2–T4 stage. A diagnostic accuracy of 83.5% and 93.3%, respectively, can be achieved for classification between early T (T1) stage cancer and normal; and advanced T (T2–T4) stage cancer and normal blood groups. This exploratory study demonstrates that the nanobiosensor based on SERS technique in conjunction with PCA-LDA has great potential as a clinical complement for different T stages detection in nasopharyngeal cancer.
PMCID: PMC3996462  PMID: 24756153
4.  Transcriptome profiling of genes and pathways associated with arsenic toxicity and tolerance in Arabidopsis 
BMC Plant Biology  2014;14:94.
Arsenic (As) is a toxic metalloid found ubiquitously in the environment and widely considered an acute poison and carcinogen. However, the molecular mechanisms of the plant response to As and ensuing tolerance have not been extensively characterized. Here, we report on transcriptional changes with As treatment in two Arabidopsis accessions, Col-0 and Ws-2.
The root elongation rate was greater for Col-0 than Ws-2 with As exposure. Accumulation of As was lower in the more tolerant accession Col-0 than in Ws-2. We compared the effect of As exposure on genome-wide gene expression in the two accessions by comparative microarray assay. The genes related to heat response and oxidative stresses were common to both accessions, which indicates conserved As stress-associated responses for the two accessions. Most of the specific response genes encoded heat shock proteins, heat shock factors, ubiquitin and aquaporin transporters. Genes coding for ethylene-signalling components were enriched in As-tolerant Col-0 with As exposure. A tolerance-associated gene candidate encoding Leucine-Rich Repeat receptor-like kinase VIII (LRR-RLK VIII) was selected for functional characterization. Genetic loss-of-function analysis of the LRR-RLK VIII gene revealed altered As sensitivity and the metal accumulation in roots.
Thus, ethylene-related pathways, maintenance of protein structure and LRR-RLK VIII-mediated signalling may be important mechanisms for toxicity and tolerance to As in the species. Here, we provide a comprehensive survey of global transcriptional regulation for As and identify stress- and tolerance-associated genes responding to As.
PMCID: PMC4021232  PMID: 24734953
Arsenate; Arabidopsis accession; Microarray
5.  Berberine Attenuates Axonal Transport Impairment and Axonopathy Induced by Calyculin A in N2a Cells 
PLoS ONE  2014;9(4):e93974.
Berberine is a primary component of the most functional extracts of Coptidis rhizome used in traditional Chinese medicine for centuries. Recent reports indicate that Berberine has the potential to prevent and treat Alzheimer's disease (AD). The previous studies reported that Calyculin A (CA) impaired the axonal transport in neuroblastoma-2a (N2a) cells. Berberine attenuated tau hyperphosphorylation and cytotoxicity induced by CA. Our study aimed at investigating the effects of Berberine on the axonal transport impairment induced by CA in N2a cells. The results showed that Berberine could protect the cell from CA -induced toxicity in metabolism and viability, as well as hyperphosphorylation of tau and neurofilaments (NFs). Furthermore, Berberine could reverse CA-induced axonal transport impairment significantly. Berberine also partially reversed the phosphorylation of the catalytic subunit of PP-2A at Tyrosine 307, a crucial site negatively regulating the activity of PP-2A, and reduced the levels of malondialdehyde and the activity of superoxide dismutase, markers of oxidative stress, induced by CA. The present work for the first time demonstrates that Berberine may play a role in protecting against CA-induced axonal transport impairment by modulating the activity of PP-2A and oxidative stress. Our findings also suggest that Berberine may be a potential therapeutic drug for AD.
PMCID: PMC3979860  PMID: 24713870
6.  Identification of a 24-Gene Prognostic Signature That Improves the European LeukemiaNet Risk Classification of Acute Myeloid Leukemia: An International Collaborative Study 
Journal of Clinical Oncology  2013;31(9):1172-1181.
To identify a robust prognostic gene expression signature as an independent predictor of survival of patients with acute myeloid leukemia (AML) and use it to improve established risk classification.
Patients and Methods
Four independent sets totaling 499 patients with AML carrying various cytogenetic and molecular abnormalities were used as training sets. Two independent patient sets composed of 825 patients were used as validation sets. Notably, patients from different sets were treated with different protocols, and their gene expression profiles were derived using different microarray platforms. Cox regression and Kaplan-Meier methods were used for survival analyses.
A prognostic signature composed of 24 genes was derived from a meta-analysis of Cox regression values of each gene across the four training sets. In multivariable models, a higher sum value of the 24-gene signature was an independent predictor of shorter overall (OS) and event-free survival (EFS) in both training and validation sets (P < .01). Moreover, this signature could substantially improve the European LeukemiaNet (ELN) risk classification of AML, and patients in three new risk groups classified by the integrated risk classification showed significantly (P < .001) distinct OS and EFS.
Despite different treatment protocols applied to patients and use of different microarray platforms for expression profiling, a common prognostic gene signature was identified as an independent predictor of survival of patients with AML. The integrated risk classification incorporating this gene signature provides a better framework for risk stratification and outcome prediction than the ELN classification.
PMCID: PMC3595425  PMID: 23382473
7.  53BP1 is a reader of the DNA damage-induced H2A Lys15 ubiquitin mark 
Nature  2013;499(7456):50-54.
53BP1 (TP53BP1) is a chromatin-associated factor that promotes immunoglobulin class switching and DNA double-strand break (DSB) repair by non-homologous end joining. To accomplish its function in DNA repair, 53BP1 accumulates at DSB sites downstream of the RNF168 ubiquitin ligase. How ubiquitin recruits 53BP1 to break sites remains enigmatic since its relocalization involves recognition of H4 Lys20 (H4K20) methylation by its Tudor domain. Here we elucidate how 53BP1 is recruited to the chromatin that flanks DSB sites. We show that 53BP1 recognizes mono-nucleosomes containing dimethylated H4K20 (H4K20me2) and H2A ubiquitylated on Lys15 (H2AK15ub), the latter being a product of RNF168 action on chromatin. 53BP1 binds to nucleosomes minimally as a dimer using its previously characterized methyl-lysine-binding Tudor domain and a C-terminal extension, termed the ubiquitylation-dependent recruitment (UDR) motif, which interacts with the epitope formed by H2AK15ub and its surrounding residues on the H2A tail. 53BP1 is therefore a bivalent histone modification reader that recognizes a histone “code” produced by DSB signaling.
PMCID: PMC3955401  PMID: 23760478 CAMSID: cams3939
8.  Application of Highly Purified Electrolyzed Chlorine Dioxide for Tilapia Fillet Disinfection 
The Scientific World Journal  2014;2014:619038.
This research aimed to develop an electrolysis method to generate high-concentration chlorine dioxide (ClO2) for tilapia fillet disinfection. The designed generator produced up to 3500 ppm of ClO2 at up to 99% purity. Tilapia fillets were soaked in a 400 ppm ClO2 solution for 5, 10, and 25 min. Results show that total plate counts of tilapia, respectively, decreased by 5.72 to 3.23, 2.10, and 1.09 log CFU/g. In addition, a 200 ppm ClO2 solution eliminated coliform bacteria and Escherichia coli in 5 min with shaking treatment. Furthermore, ClO2 and trihalomethanes (THMs) residuals on tilapia fillets were analyzed by GC/MS and were nondetectable (GC-MS detection limit was 0.12 ppb). The results conform to Taiwan's environmental protection regulations and act governing food sanitation.
PMCID: PMC3947783  PMID: 24696651
9.  Chondroprotective Activity of Murraya exotica through Inhibiting β-Catenin Signaling Pathway 
Osteoarthritis (OA) is a degenerative joint disease that affects millions of people. Currently, there is no effective drug treatment for it. The purpose of this study is to investigate the chondroprotective effects of Murraya exotica (L.) on OA. The rat OA models were duplicated to prepare for separating OA chondrocytes, synovial fluid (SF), and serum containing M. exotica (50 mg/kg, 100 mg/kg, and 200 mg/kg), M. exotica showed the activity of decreasing the contents of TNF-α and IL-1β in SF and the chondrocyte apoptosis in a dose-dependent manner. To investigate the probable mechanism, quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were used to determine gene expression and protein profiles, respectively. The results reveal that M. exotica can downregulate mRNA and protein expressions of β-catenin and COX-2 and reporter activity significantly. Conclusively, M. exotica exhibits antiapoptotic chondroprotective activity probably through inhibiting β-catenin signaling.
PMCID: PMC3880701  PMID: 24454514
10.  The Ginger-shaped Asteroid 4179 Toutatis: New Observations from a Successful Flyby of Chang'e-2 
Scientific Reports  2013;3:3411.
On 13 December 2012, Chang'e-2 conducted a successful flyby of the near-Earth asteroid 4179 Toutatis at a closest distance of 770 ± 120 meters from the asteroid's surface. The highest-resolution image, with a resolution of better than 3 meters, reveals new discoveries on the asteroid, e.g., a giant basin at the big end, a sharply perpendicular silhouette near the neck region, and direct evidence of boulders and regolith, which suggests that Toutatis may bear a rubble-pile structure. Toutatis' maximum physical length and width are (4.75 × 1.95 km) ±10%, respectively, and the direction of the +z axis is estimated to be (250 ± 5°, 63 ± 5°) with respect to the J2000 ecliptic coordinate system. The bifurcated configuration is indicative of a contact binary origin for Toutatis, which is composed of two lobes (head and body). Chang'e-2 observations have significantly improved our understanding of the characteristics, formation, and evolution of asteroids in general.
PMCID: PMC3860288  PMID: 24336501
11.  Optical imaging of head and neck squamous cell carcinoma in vivo using arginine-glycine-aspartic acid peptide conjugated near-infrared quantum dots 
OncoTargets and therapy  2013;6:1779-1787.
Molecular imaging plays a key role in personalized medicine and tumor diagnosis. Quantum dots with near-infrared emission spectra demonstrate excellent tissue penetration and photostability, and have recently emerged as important tools for in vivo tumor imaging. Integrin αvβ3 has been shown to be highly and specifically expressed in endothelial cells of tumor angiogenic vessels in almost all types of tumors, and specifically binds to the peptide containing arginine-glycine-aspartic acid (RGD). In this study, we conjugated RGD with quantum dots with emission wavelength of 800 nm (QD800) to generate QD800-RGD, and used it via intravenous injection as a probe to image tumors in nude mice bearing head and neck squamous cell carcinoma (HNSCC). Twelve hours after the injection, the mice were still alive and were sacrificed to isolate tumors and ten major organs for ex vivo analysis to localize the probe in these tissues. The results showed that QD800-RGD was specifically targeted to integrin αvβ3 in vitro and in vivo, producing clear tumor fluorescence images after the intravenous injection. The tumor-to-background ratio and size of tumor image were highest within 6 hours of the injection and declined significantly at 9 hours after the injection, but there was still a clearly visible tumor image at 12 hours. The greatest amount of QD800-RGD was found in liver and spleen, followed by tumor and lung, and a weak fluorescence signal was seen in tibia. No detectable signal of QD800-RGD was found in brain, heart, kidney, testis, stomach, or intestine. Our study demonstrated that using integrin αvβ3 as target, it is possible to use intravenously injected QD800-RGD to generate high quality images of HNSCC, and the technique offers great potential in the diagnosis and personalized therapy for HNSCC.
PMCID: PMC3855103  PMID: 24324343
nanotechnology; near-infrared fluorescence; tumor angiogenic vessel; head and neck cancer; in vivo imaging
12.  Nek9 regulates spindle organization and cell cycle progression during mouse oocyte meiosis and its location in early embryo mitosis 
Cell Cycle  2012;11(23):4366-4377.
Nek9 (also known as Nercc1), a member of the NIMA (never in mitosis A) family of protein kinases, regulates spindle formation, chromosome alignment and segregation in mitosis. Here, we showed that Nek9 protein was expressed from germinal vesicle (GV) to metaphase II (MII) stages in mouse oocytes with no detectable changes. Confocal microscopy identified that Nek9 was localized to the spindle poles at the metaphase stages and associated with the midbody at anaphase or telophase stage in both meiotic oocytes and the first mitotic embyros. Depletion of Nek9 by specific morpholino injection resulted in severely defective spindles and misaligned chromosomes with significant pro-MI/MI arrest and failure of first polar body (PB1) extrusion. Knockdown of Nek9 also impaired the spindle-pole localization of γ-tubulin and resulted in retention of the spindle assembly checkpoint protein Bub3 at the kinetochores even after 10 h of culture. Live-cell imaging analysis also confirmed that knockdown of Nek9 resulted in oocyte arrest at the pro-MI/MI stage with abnormal spindles, misaligned chromosomes and failed polar body emission. Taken together, our results suggest that Nek9 may act as a MTOC-associated protein regulating microtubule nucleation, spindle organization and, thus, cell cycle progression during mouse oocyte meiotic maturation, fertilization and early embryo cleavage.
PMCID: PMC3552919  PMID: 23159858
meiosis; microtubule-organizing center (MTOC) spindle; oocyte; γ-tubulin
13.  Use of an in vivo Animal Model for Assessing the Role of Integrin α6β4 and Syndecan-1 in Early Steps in Papillomavirus Infection 
Virology  2012;433(2):395-400.
Human papillomaviruses (HPV) are small DNA tumor viruses. HPV infection requires entry of virions into epithelial host cells that support the viral life cycle. Here, we used an in vivo mouse model, in which HPV pseudoviruses (PVs) are scored for their ability to transduce reporter genes, to test the role of various cellular proteins in entry. We initially investigated the role of integrin α6β4 in mediating early steps of HPV infection. Deficiency of integrin α6β4 modestly but significantly suppressed reporter-gene transduction by PVs in conditional integrin β4 knockout mice. We also investigated the role of syndecan 1, a heparin sulfate proteoglycan (HSPG) for its role in HPV infection. We didn’t see a significant reduction in reporter-gene transduction by PVs in syndecan-1 null mice. This indicates that this HSPG is not essential for early steps in HPV infection, but does not discount a need of other HSPGs in mediating HPV infection.
PMCID: PMC3466357  PMID: 22995187
Human Papillomavirus (HPV); Integrin α6β4 (Int α6β4); Heparin Sulfate Proteoglycans (HSPGs); Syndecan-1 (Sdc-1)
14.  White Matter Disruptions in Adolescents Exposed to Childhood Maltreatment and Vulnerability to Psychopathology 
Neuropsychopharmacology  2012;37(12):2693-2701.
Childhood maltreatment has been known to produce long-lasting impairments in behavioral, cognitive and social functioning, but their underlying mechanisms are not well-understood. A better understanding of their underlying mechanisms will aid in developing effective preventive interventions. Nineteen adolescent volunteers with no personal history of a psychiatric illness, but who were exposed to maltreatment during childhood, and 13 adolescent volunteers with no personal or family history of a psychiatric disorder (controls) underwent diffusion tensor imaging (DTI) studies. The participants were then followed longitudinally at 6-month intervals for up to 5 years to determine the onset of mood and substance use disorders. The associations among fractional anisotropy (FA) values obtained from the DTI scans at baseline and psychopathology at follow-up were examined. At baseline, adolescents exposed to childhood maltreatment had significantly lower FA values in the left and right superior longitudinal fasciculi, right cingulum bundle projecting to the hippocampus, left inferior fronto-occipital fasciculus, and splenium of the corpus callosum compared with controls. Adolescents who developed major depressive disorder at follow-up had significantly lower FA values in the superior longitudinal fasciculi and the right cingulum-hippocampal projection compared with their counterparts who did not develop the illness. Adolescents who developed substance use disorder during follow-up had significantly lower FA values in the right cingulum-hippocampal projection than their counterparts without the disorder. These preliminary results suggest that white matter disruptions observed in adolescents exposed to childhood maltreatment may be associated with increased vulnerability to psychopathology, specifically depressive and substance use disorders.
PMCID: PMC3473335  PMID: 22850736
adolescent; DTI; maltreatment; psychopathology; superior longitudinal fasciculus; white matter; addiction & substance abuse; adolescent; biological psychiatry; depression; unipolar/bipolar; DTI; maltreatment; neuroanatomy; psychopathology; superior longitudinal fasciculus
15.  Blockade of miR-150 maturation by MLL-fusion/MYC/LIN-28 is required for MLL-associated leukemia 
Cancer cell  2012;22(4):524-535.
Expression of microRNAs (miRNAs) is under stringent regulation at both transcriptional and post-transcriptional levels. Disturbance at either level could cause dysregulation of miRNAs. Here we show that MLL fusion proteins negatively regulate production of miR-150, an miRNA widely repressed in acute leukemia, by blocking miR-150 precursors from being processed to mature miRNAs through MYC/LIN28 functional axis. Forced expression of miR-150 dramatically inhibited leukemic cell growth and delayed MLL-fusion-mediated leukemogenesis, likely through targeting FLT3 and MYB and thereby interfering with the HOXA9/MEIS1/FLT3/MYB signaling network, which in turn caused downregulation of MYC/LIN28. Collectively, we revealed a MLL-fusion/MYC/LIN28⊣miR-150⊣FLT3/MYB/HOXA9/MEIS1 signaling circuit underlying the pathogenesis of leukemia, where miR-150 functions as a pivotal gatekeeper and its repression is required for leukemogenesis.
PMCID: PMC3480215  PMID: 23079661
miR-150; MLL-associated leukemia; MYC; LIN28; FLT3; MYB; HOXA9; MEIS1; microRNA maturation; signaling axis; leukemogenesis
16.  Correction: Genetic Map Construction and Quantitative Trait Locus (QTL) Detection of Growth-Related Traits in Litopenaeus vannamei for Selective Breeding Applications 
PLoS ONE  2013;8(10):10.1371/annotation/80183e4b-b1b4-48cc-b307-865af97df0ce.
PMCID: PMC3805606  PMID: 24204445
17.  Genetic Map Construction and Quantitative Trait Locus (QTL) Detection of Growth-Related Traits in Litopenaeus vannamei for Selective Breeding Applications 
PLoS ONE  2013;8(9):e75206.
Growth is a priority trait from the point of view of genetic improvement. Molecular markers linked to quantitative trait loci (QTL) have been regarded as useful for marker-assisted selection (MAS) in complex traits as growth. Using an intermediate F2 cross of slow and fast growth parents, a genetic linkage map of Pacific whiteleg shrimp, Litopenaeusvannamei, based on amplified fragment length polymorphisms (AFLP) and simple sequence repeats (SSR) markers was constructed. Meanwhile, QTL analysis was performed for growth-related traits. The linkage map consisted of 451 marker loci (429 AFLPs and 22 SSRs) which formed 49 linkage groups with an average marker space of 7.6 cM; they spanned a total length of 3627.6 cM, covering 79.50% of estimated genome size. 14 QTLs were identified for growth-related traits, including three QTLs for body weight (BW), total length (TL) and partial carapace length (PCL), two QTLs for body length (BL), one QTL for first abdominal segment depth (FASD), third abdominal segment depth (TASD) and first abdominal segment width (FASW), which explained 2.62 to 61.42% of phenotypic variation. Moreover, comparison of linkage maps between L. vannamei and Penaeusjaponicus was applied, providing a new insight into the genetic base of QTL affecting the growth-related traits. The new results will be useful for conducting MAS breeding schemes in L. vannamei.
PMCID: PMC3783498  PMID: 24086466
18.  Regulation of the timing of oligodendrocyte differentiation: mechanisms and perspectives 
Neuroscience bulletin  2013;29(2):155-164.
Axonal myelination is an essential process for normal functioning of vertebrate central nervous system. Proper formation of myelin sheaths around axons depends on the timely differentiation of oligodendrocytes. It was observed that the differentiation occurs on a predictable schedule both in culture and during development. However, the timing mechanisms for oligodendrocyte differentiation during normal development have not been fully uncovered. Recent studies have identified a large number of regulatory factors including the cell-intrinsic factors and extracellular signals that could control the timing of oligodendrocyte differentiation. Here we provide a mechanistic and critical review on the timing control of oligodendrocyte differentiation.
PMCID: PMC3761796  PMID: 23456566
oligodendrocytes; differentiation; timing; remyelination
19.  microRNAs and glial cell development 
Mounting evidence indicates that miRNAs play important roles in the control of glial cell development in the central nervous system. Suppression of miRNA formation disrupts the initial generation of oligodendrocyte progenitor cells from the ventricular neuroprogenitor cells in embryonic spinal cord. miRNAs also regulate the later events of oligodendrocyte development including cell proliferation, maturation and myelin formation. In addition, miRNAs are essential for the development of astrocytes, and inhibition of miRNA genesis completely blocks astrogliogenesis in the spinal cord.
PMCID: PMC3762876  PMID: 21555783
Oligodendrocytes; astrocytes; spinal cord; miRNA; regulation
20.  Distinctive disruption patterns of white matter tracts in Alzheimer’s disease with full diffusion tensor characterization 
Neurobiology of Aging  2011;33(9):2029-2045.
To characterize the white matter structural changes at the tract level and tract group level, comprehensive analysis with four metrics derived from DTI, fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AxD) and radial diffusivity (RD), was conducted. Tract groups, namely limbic, commissural, association and projection tracts, include white matter tracts of similar functions. DTI data were acquired from 61 subjects (26 AD, 11 subjects with amnestic mild cognitive impairment or aMCI, 24 age-matched controls). An atlas-based approach was used to survey 30 major cerebral white matter tracts with the measurements of FA, MD, AxD and RD. Regional cortical atrophy and cognitive functions of AD patients were also measured to correlate with the structural changes of white matter. Synchronized structural changes of cingulum bundle and fornix, both of which are part of limbic tract group, were revealed. Widespread yet distinctive structural changes were found in limbic, commissural, association and projection tract groups between control and AD subjects. Specifically, FA, MD and RD of limbic tracts, FA, MD, AxD and RD of commissural tracts, MD, AxD and RD of association tracts and MD and AxD of projection tracts are significantly different between AD patients and control subjects. In contrast, the comparison between aMCI and control subjects shows disruption only in the limbic and commissural tract groups of aMCI subjects. MD values of all tract groups of AD patients are significantly correlated to cognitive functions. Difference between AD and control and that between MCI and control indicates a progression pattern of white matter disruption from limbic and commissural tract group to other tract groups. High correlation between FA, MD and RD measurements from limbic tracts and cortical atrophy suggests the disruption of the limbic tract group is caused by the neuronal damage.
PMCID: PMC3227739  PMID: 21872362
Alzheimer’s disease; atlas; DTI; white matter tract; tract group; biomarker
21.  Regional changes of cortical mean diffusivities with aging after correction of partial volume effects 
NeuroImage  2012;62(3):1705-1716.
Accurately measuring the cortical mean diffusivity (MD) derived from diffusion tensor imaging (DTI) at the comprehensive lobe, gyral and voxel level of young, elderly healthy brains and those with Alzheimer's disease (AD) may provide insights on heterogeneous cortical microstructural changes caused by aging and AD. Due to partial volume effects (PVE), the measurement of cortical MD is overestimated with contamination of cerebrospinal fluid (CSF). The bias is especially severe for aging and AD brains because of significant cortical thinning of these brains. In this study, we aimed to quantitatively characterize the unbiased regional cortical MD changes due to aging and AD and delineate the effects of cortical thinning of elderly healthy and AD groups on MD measurements. DTI and T1-weighted images of 14 young, 15 elderly healthy subjects and 17 AD patients were acquired. With the parcellated cortical gyri and lobes from T1 weighted image transformed to DTI, regional cortical MD of all subjects before and after PVE correction were measured. CSF contamination model was used to correct bias of MD caused by PVE. Compared to cortical MD of young group, significant increases of corrected MD for elderly healthy and AD groups were found only in frontal and limbic regions, respectively, while there were significant increases of uncorrected MD all over the cortex. Uncorrected MD are significantly higher in limbic and temporal gyri in AD group, compared to those in elderly healthy group but higher MD only remained in limbic gyri after PVE correction. Cortical thickness was also measured for all groups. The correlation slopes between cortical MD and thickness for elderly healthy and AD groups were significantly decreased after PVE correction compared to before correction while no significant change of correlation slope was detected for young group. It suggests that the cortical thinning in elderly healthy and AD groups is a significant contributor to the bias of uncorrected cortical MD measurement. The established comprehensive unbiased cortical MD profiles of young, elderly healthy subjects and AD patients at the lobe, gyral and voxel level may serve as clinical references for cortical microstructure.
PMCID: PMC3574164  PMID: 22683383
DTI; Cortex; Mean diffusivity; Aging; Alzheimer's disease; Unbiased; Partial volume effects
22.  Two isoforms of HOXA9 function differently but work synergistically in human MLL-rearranged leukemia 
Blood cells, molecules & diseases  2012;49(2):102-106.
HOXA9 plays a critical role in both normal hematopoiesis and leukemogenesis, particularly in the development and maintenance of mixed lineage leukemia (MLL)-rearranged leukemia. Through reverse transcription polymerase chain reaction (RT-PCR) analysis of HOXA9 transcripts in human leukemia and normal bone marrow samples, we identified a truncated isoform of HOXA9, namely HOXA9T, and found that both HOXA9T and canonical HOXA9 were highly expressed in leukemia cell lines bearing MLL rearrangements, relative to human normal bone marrow cells or other subtypes of leukemia cells. A frameshift in HOXA9T in exon I causes a premature stop codon upstream of the PBX binding domain and the homeodomain, which leads to the generation of a non-homeodomain-containing protein. Unlike the canonical HOXA9, HOXA9T alone cannot transform normal bone marrow progenitor cells. Moreover, HOXA9T cannot cooperate with MEIS1 to transform cells, despite the presence of a MEIS1-binding domain. Remarkably, although the truncated isoforms of many proteins function as dominant-negative competitors or inhibitors of their full-length counterparts, this is not the case for HOXA9T; instead, HOXA9T synergized with HOXA9 in transforming mouse normal bone marrow progenitor cells through promoting self-renewal and proliferation of the cells. Collectively, our data indicate that both truncated and full-length forms of HOXA9 are highly expressed in human MLL-rearranged leukemia, and the truncated isoform of HOXA9 might also play an oncogenic role by cooperating with canonical HOXA9 in cell transformation and leukemogenesis.
PMCID: PMC3399022  PMID: 22633751
HOXA9; HOXA9T; isoforms; leukemia
23.  Association with Soil Bacteria Enhances p38-Dependent Infection Resistance in Caenorhabditis elegans 
Infection and Immunity  2013;81(2):514-520.
The importance of our inner microbial communities for proper immune responses against invading pathogens is now well accepted, but the mechanisms underlying this protection are largely unknown. In this study, we used Caenorhabditis elegans to investigate such mechanisms. Since very little is known about the microbes interacting with C. elegans in its natural environment, we began by taking the first steps to characterize the C. elegans microbiota. We established a natural-like environment in which initially germfree, wild-type larvae were grown on enriched soil. Bacterial members of the adult C. elegans microbiota were isolated by culture and identified using 16S rRNA gene sequencing. Using pure cultures of bacterial isolates as food, we identified two, Bacillus megaterium and Pseudomonas mendocina, that enhanced resistance to a subsequent infection with the Gram-negative pathogen Pseudomonas aeruginosa. Whereas protection by B. megaterium was linked to impaired egg laying, corresponding to a known trade-off between fecundity and resistance, the mechanism underlying protection conferred by P. mendocina depended on weak induction of immune genes regulated by the p38 MAPK pathway. Disruption of the p38 ortholog, pmk-1, abolished protection. P. mendocina enhanced resistance to P. aeruginosa but not to the Gram-positive pathogen Enterococcus faecalis. Furthermore, protection from P. aeruginosa was similarly induced by a P. aeruginosa gacA mutant with attenuated virulence but not by a different C. elegans-associated Pseudomonas sp. isolate. Our results support a pivotal role for the conserved p38 pathway in microbiota-initiated immune protection and suggest that similarity between microbiota members and pathogens may play a role in such protection.
PMCID: PMC3553824  PMID: 23230286
24.  Topological insulator bismuth selenide as a theranostic platform for simultaneous cancer imaging and therapy 
Scientific Reports  2013;3:1998.
Employing theranostic nanoparticles, which combine both therapeutic and diagnostic capabilities in one dose, has promise to propel the biomedical field toward personalized medicine. Here we investigate the theranostic properties of topological insulator bismuth selenide (Bi2Se3) in in vivo and in vitro system for the first time. We show that Bi2Se3 nanoplates can absorb near-infrared (NIR) laser light and effectively convert laser energy into heat. Such photothermal conversion property may be due to the unique physical properties of topological insulators. Furthermore, localized and irreversible photothermal ablation of tumors in the mouse model is successfully achieved by using Bi2Se3 nanoplates and NIR laser irradiation. In addition, we also demonstrate that Bi2Se3 nanoplates exhibit strong X-ray attenuation and can be utilized for enhanced X-ray computed tomography imaging of tumor tissue in vivo. This study highlights Bi2Se3 nanoplates could serve as a promising platform for cancer diagnosis and therapy.
PMCID: PMC3683666  PMID: 23770650
25.  Altering Hirsutism Through Ovulation Induction in Women With Polycystic Ovary Syndrome 
Obstetrics and Gynecology  2012;119(6):1151-1156.
Many women with polycystic ovary syndrome (PCOS) experience infertility and hirsutism and often seek treatment for both concurrently. We investigated whether women who ovulate in response to treatment with clomiphene citrate), metformin, or both would have greater improvement in hirsutism compared to those who did not ovulate.
This is a secondary analysis evaluating the change in Ferriman-Gallwey score for the hirsute women (n = 505, 80.7%) from the Pregnancy in Polycystic Ovary Syndrome 1 study. This was a prospective, randomized, doubled-blind trial of 626 women with PCOS and infertility recruited from 12 university sites. They were treated with clomiphene citrate, metformin, or both (combination) for up to six cycles, and hirsutism evaluators were blinded to group assignment.
There was a significant decrease in the Ferriman-Gallwey score between baseline and completion of the study in each of the three individual groups (clomiphene citrate, p=0.024; metformin, p=0.005; combination, p<0.001). There was no significant difference in the degree to which the hirsutism score changed when comparing the three groups (p=0.44). The change in hirsutism was not associated with the duration of treatment or with the presence or absence of ovulation.
In infertile hirsute women with PCOS, treatment with clomiphene citrate, metformin, or both for up to 6 cycles does not alter hirsutism.
Clinical Trial Registration,, NCT00068861.
PMCID: PMC3360417  PMID: 22617579

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