Duc Nguyen | University of Arkansas (original) (raw)

Papers by Duc Nguyen

Journal of Cardiac Failure, 2015

Journal of Cardiac Failure, 2014

The Journal of experimental medicine, 2016

Coordinated repression of gene expression by evolutionarily conserved microRNA (miRNA) clusters a... more Coordinated repression of gene expression by evolutionarily conserved microRNA (miRNA) clusters and paralogs ensures that miRNAs efficiently exert their biological impact. Combining both loss- and gain-of-function genetic approaches, we show that the miR-23∼27∼24 clusters regulate multiple aspects of T cell biology, particularly helper T (Th) 2 immunity. Low expression of this miRNA family confers proper effector T cell function at both physiological and pathological settings. Further studies in T cells with exaggerated regulation by individual members of the miR-23∼27∼24 clusters revealed that miR-24 and miR-27 collaboratively limit Th2 responses through targeting IL-4 and GATA3 in both direct and indirect manners. Intriguingly, although overexpression of the entire miR-23 cluster also negatively impacts other Th lineages, enforced expression of miR-24, in contrast to miR-23 and miR-27, actually promotes the differentiation of Th1, Th17, and induced regulatory T cells, implying tha...

Oncotarget, Jan 25, 2016

The heterogenous ribonucleoprotein A18 (hnRNP A18) promotes tumor growth by coordinating the tran... more The heterogenous ribonucleoprotein A18 (hnRNP A18) promotes tumor growth by coordinating the translation of selected transcripts associated with proliferation and survival. hnRNP A18 binds to and stabilizes the transcripts of pro-survival genes harboring its RNA signature motif in their 3'UTRs. hnRNP A18 binds to ATR, RPA, TRX, HIF-1a and several protein translation factor mRNAs on polysomes and increases de novo protein translation under cellular stress. Most importantly, down regulation of hnRNP A18 decreases proliferation, invasion and migration in addition to significantly reducing tumor growth in two mouse xenograft models, melanoma and breast cancer. Moreover, tissue microarrays performed on human melanoma, prostate, breast and colon cancer indicate that hnRNP A18 is over expressed in 40 to 60% of these malignant tissue as compared to normal adjacent tissue. Immunohistochemistry data indicate that hnRNP A18 is over expressed in the stroma and hypoxic areas of human tumors....

Computing Systems in Engineering, 1991

... Press pie PARALLEL-VECTOR COMPUTATION FOR LINEAR STRUCTURAL ANALYSIS AND NON-LINEAR UNCONSTRA... more ... Press pie PARALLEL-VECTOR COMPUTATION FOR LINEAR STRUCTURAL ANALYSIS AND NON-LINEAR UNCONSTRAINED OPTIMIZATION PROBLEMS DT NGUVEN,~" OO STORAASLI,~ EA CARMONA, M. AL-NASRA,t Y ... 4. F(ct)min using Golden Block Search algorithm. ...

2007 Electrical Insulation Conference and Electrical Manufacturing Expo, 2007

ABSTRACT For many years, partial discharge (PD) activity has been used in air-cooled generators a... more ABSTRACT For many years, partial discharge (PD) activity has been used in air-cooled generators as one of the important indicators of degradation mechanisms in stator winding insulation. Up to a certain level, these degradation processes are slow. Under normal operation, PD measurement and trending can generally indicate that not only electrical but also mechanical, thermal or ambient (contamination) degradation processes are occurring. Partial discharge activity in air-cooled generators also produces ozone so that the presence of ozone inside and around the generator enclosure is indicative of PD activity. In some cases, the ozone concentration produced by sustained PD activity can reach such levels that it becomes a health hazard for plant personnel. Hazardous levels were recorded in 1991, after 12 years of operation, inside the enclosure of the four 184-MVA hydro generators at BC hydro's peace canyon (PCN) generating station, revealing a situation that was probably active for some years. Results from annual PD measurement performed using PDA (partial discharge analysis) techniques showed an asymmetry in favor of positive discharges that can be the result of slot discharges. Phase resolved partial discharge (PRPD) measurements combined with ozone measurements taken all around the rear perimeter of the generator core were used to confirm the nature of the PDs. Since one of the generators was scheduled for a complete stator winding and core replacement in 2006, an exhaustive investigation was performed before and after replacing the stator. Some stator bars were removed from the slots for visual inspection and extensive laboratory testing. This paper presents results of the on-line PD and ozone measurements, together with findings from visual inspection and laboratory investigations of the retrieved bars. These results were analyzed collectively in order to establish the root cause of the insulation problem as well as the deterioration mechanism of the generator stator wind- - ing. Finally, a new pre-installation testing procedure is recommended to prevent such a costly insulation problem from occurring again.

Chemistry - A European Journal, 2015

Access to hydroxy-functionalized P-chiral phosphine-boranes has become an important field in the ... more Access to hydroxy-functionalized P-chiral phosphine-boranes has become an important field in the synthesis of P-stereogenic compounds used as ligands in asymmetric catalysis. A family of optically pure α and β-hydroxyalkyl tertiary phosphine-boranes has been prepared by using a three-step procedure from readily accessible enantiopure adamantylphosphinate, obtained by semi-preparative HPLC on multigram scale. Firstly, a two-step one-pot transformation affords the enantiopure hydroxyalkyl tertiary phosphine oxides in good yields and enantioselectivities. The third step, BH3 -mediated reduction, allows the formation of the desired phosphine-boranes with excellent stereospecifity. The mechanistic study of this reduction provides new evidence to elucidate the crucial role of the pendant hydroxy group and the subsequent activation of the PO bond by the boron atom.

Infection control and hospital epidemiology, Jan 17, 2015

BACKGROUND In November and December 2012, 6 patients at a hemodialysis clinic were given a diagno... more BACKGROUND In November and December 2012, 6 patients at a hemodialysis clinic were given a diagnosis of new hepatitis C virus (HCV) infection. OBJECTIVE To investigate the outbreak to identify risk factors for transmission. METHODS A case patient was defined as a patient who was HCV-antibody negative on clinic admission but subsequently was found to be HCV-antibody positive from January 1, 2008, through April 30, 2013. Patient charts were reviewed to identify and describe case patients. The hypervariable region 1 of HCV from infected patients was tested to assess viral genetic relatedness. Infection control practices were evaluated via observations. A forensic chemiluminescent agent was used to identify blood contamination on environmental surfaces after cleaning. RESULTS Eighteen case patients were identified at the clinic from January 1, 2008, through April 30, 2013, resulting in an estimated 16.7% attack rate. Analysis of HCV quasispecies identified 4 separate clusters of transmi...

Journal of Cancer Research and Clinical Oncology

Glioblastoma multiforme (GBM) is a very aggressive and locally invasive tumor. The current standa... more Glioblastoma multiforme (GBM) is a very aggressive and locally invasive tumor. The current standard of care is partial brain radiation therapy (60 Gy) concurrently with the alkylating agent temozolomide (TMZ). However, patients' survival remains poor (6-12 months) mainly due to local and diffuse (distant) recurrence. The possibility to promote hyper radiosensitivity (HRS) with low dose radiation may contribute to improve outcome. Here, we evaluated the effect of Vorinostat(SAHA) and TMZ on glioblastoma cells' sensitivity to low dose radiation. Clonogenic survivals were performed on D54 (p53 and PTEN wild type) and U118 (p53 and PTEN mutants) cells exposed to clinically relevant doses of Vorinostat(SAHA) and TMZ and increasing radiation doses. Apoptosis was measured by the activation of caspase-3 and the role of p53 and PTEN were evaluated with the p53 inhibitor pifithrin α and the PI3K/AKT pathway inhibitor LY29002. Vorinostat(SAHA) promoted HRS at doses as low as 0.25 Gy in...

Infection control and hospital epidemiology, Jan 11, 2015

Reports of bloodstream infections caused by methicillin-resistant Staphylococcus aureus among chr... more Reports of bloodstream infections caused by methicillin-resistant Staphylococcus aureus among chronic hemodialysis patients to 2 Centers for Disease Control and Prevention surveillance systems (National Healthcare Safety Network Dialysis Event and Emerging Infections Program) were compared to evaluate completeness of reporting. Many methicillin-resistant S. aureus bloodstream infections identified in hospitals were not reported to National Healthcare Safety Network Dialysis Event. Infect. Control Hosp. Epidemiol. 2015;00(0):1-3.

National Conference on Artificial Intelligence, 2007

48th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2007

Efficient numerical procedures (modal method) for solving large-scale, sparse, nonlinear largedef... more Efficient numerical procedures (modal method) for solving large-scale, sparse, nonlinear largedeflection random vibration problems are reviewed. Solution for the small number (say less than 100) of lowest linear eigen-pairs needs to be solved for only once, in order to transform nonlinear ...

2003 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, 2003

In order to assess the quality of stator winding insulation, laboratory and field instruments mea... more In order to assess the quality of stator winding insulation, laboratory and field instruments measuring the charge and discharge currents flowing through rotating machine ground-wall winding insulation were developed. These instruments apply a dc voltage step during a variable charging time at various voltage levels followed by a discharge step during which the insulating dielectric is shorted to ground. The

Cancer Research, 2014

ABSTRACT Whole-abdominal radiotherapy (WART) is a primary method for managing gastrointestinal ca... more ABSTRACT Whole-abdominal radiotherapy (WART) is a primary method for managing gastrointestinal cancers that have disseminated into intra-abdominal tissues. While effective, this approach is limited because of the increased toxicity to normal tissue associated with combined WART and full-dose chemotherapy regimens. Recent studies have demonstrated a survival advantage in a novel treatment paradigm that allows for the safe use of full-dose systemic chemotherapy in combination with low-dose fractionated radiotherapy (LDFRT). Traditionally, radiation doses greater than 120 cGy have been used in radiotherapy because lower doses were thought to be ineffective for tumor therapy. However, we now know that LDFRT can produce hyper-radiosensitivity (HRS), a phenomenon where cells undergo apoptosis at radiation doses as low as 15 cGy, in a number of proliferating cells. The objectives of our current study were to determine whether LDFRT can induce HRS in gastrointestinal cancer cells and to identify biomarkers of chemopotentiation by LDFRT. Our data indicate that three consecutive daily fractions of 15 cGy produced HRS in gastric cancer cells and potentiated a modified regimen of docetaxel, cisplatin and 5'-fluorouracil (mDCF). Colony survival assays indicated that 15 cGy was sufficient to kill 90% of the cells when LDFRT was combined with mDCF whereas a dose almost 10 times higher (135 cGy) was needed to achieve the same rate when using conventional radiotherapy alone. RT(2) PCR Profiler™ array analysis indicated that this combined regimen upregulated dual oxidase 2 (DUOX2), an enzyme functioning in the production of hydrogen peroxide, without upregulating genes involved in DNA repair. Moreover, downregulation of DUOX2 increased radioresistance at every radiation dose tested. In addition, our data indicate that reactive oxygen species (ROS) increase up to 3.5-fold in cells exposed to LDFRT and mDCF. Furthermore, inhibition of NADPH oxidase abrogated the killing efficiency of this combined regimen. Taken together these data suggest that chemopotentiation by LDFRT in gastric cancer cells may be due, at least in part, to increased ROS production (DUOX2) without upregulation of the DNA repair machinery. These data thus provide a rationale for further explorations of potential clinical applications of LDFRT, such as in WART, as a chemopotentiator for advanced and metastatic gastric cancers.

The Journal of Organic Chemistry, 2015

A new family of H-adamantylphosphinates as universal precursors of P-stereogenic ligands was obta... more A new family of H-adamantylphosphinates as universal precursors of P-stereogenic ligands was obtained in one step from commercial chlorophosphines. Both enantiomers of these air and moisture stable intermediates can easily be separated by semi-preparative chiral HPLC in gram scale and individually undergo stereoselective transformations to afford each enantiomers of a set of P-stereogenic compounds such as secondary phosphine oxides and boron-protected monophosphines.

Clinical chemistry, 2000

Cardiac depression in severe sepsis and septic shock is characterized by left ventricular (LV) fa... more Cardiac depression in severe sepsis and septic shock is characterized by left ventricular (LV) failure. To date, it is unclear whether clinically unrecognized myocardial cell injury accompanies, causes, or results from this decreased cardiac performance. We therefore studied the relationship between cardiac troponin I (cTnI) and T (cTnT) and LV dysfunction in early septic shock. Forty-six patients were consecutively enrolled, fluid-resuscitated, and treated with catecholamines. Cardiac markers were measured at study entry and after 24 and 48 h. LV function was assessed by two-dimensional transesophageal echocardiography. Increased plasma concentrations of cTnI (>/=0.4 microgram/L) and cTnT (>/=0.1 microgram/L) were found in 50% and 36%, respectively, of the patients at one or more time points. cTnI and cTnT were significantly correlated (r = 0.847; P <0.0001). Compared with cTnI-negative patients, cTnI-positive subjects were older, presented higher Acute Physiology and Chro...

World Scientific Studies in International Economics, 2008

Critical care medicine, 2006

We investigated whether serum levels of neuron-specific enolase (NSE) and S-100beta protein could... more We investigated whether serum levels of neuron-specific enolase (NSE) and S-100beta protein could be used to evaluate cerebral injury and to predict outcome in severe sepsis and severe septic shock. Prospective study. University hospital. In 170 consecutively enrolled patients with severe sepsis and septic shock, serum S-100beta and NSE were measured daily during four consecutive days after intensive care unit admission. Admission Glasgow Coma Scale before sedation and daily Sequential Organ Failure Assessment scores were recorded in all patients. Acute encephalopathy was defined as either a state of agitation, confusion, irritability, and convulsions (type A) or characterized by somnolence, stupor, and coma (type B) and persistently observed during 72 hrs after withdrawing sedation. When clinically indicated, contrast computed tomography or magnetic resonance imaging were performed to evaluate brain injury. S-100beta and NSE increased in, respectively, 72 (42%) and 90 (53%) patient...