Papers by Duy Hiệp Nguyễn
Current therapeutic approaches in neovascular age-related macular degeneration
Discovery medicine, 2013
Age-related macular degeneration (AMD) is the leading eye disease to cause visual impairment in t... more Age-related macular degeneration (AMD) is the leading eye disease to cause visual impairment in the elderly. Neovascular AMD is a type of advanced AMD that is characterized by pathologic proliferation and leakage of abnormal blood vessels in the eye. While the pathogenesis of neovascular AMD is not completely known, one of the important milestones in neovascular AMD research was the identification of vascular endothelial growth factor (VEGF) as a major stimulus of abnormal angiogenesis that can be targeted for intravitreal treatment. Anti-VEGF therapies that neutralize or block the induction of angiogenesis by VEGF have recently revolutionized the therapeutic approach to neovascular AMD. The scientific literature regarding the efficacy and safety of anti-VEGF treatment has been hugely enriched with results from various recent randomized clinical trials involving the three most commonly utilized anti-VEGF pharmacologic agents--ranibizumab, bevacizumab, and aflibercept. The potential ...
Ophthalmic Genetics, 2014
Human Genetics, 2013
Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal diseases. The prevalence ... more Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal diseases. The prevalence of RP and the mutation spectrum vary across populations. Hispanic people account for approximately 17% of the United States population, and the genetic etiologies of RP of this ethnic group still remain not well defined. Utilizing next-generation sequencing (NGS), we screened mutations in known retinal diseasecausing genes in an RP cohort of 35 unrelated Hispanic probands from the Miami area. We achieved a solving rate of 66% and identified 15 novel putative pathogenic mutations, including a frequent founder mutation disrupting PRPF31 splicing. Our data show that the mutation spectrum of Hispanic RP receives a significant impact from disease-causing alleles of Spanish origin and may also contain population-specific alleles. Retinitis pigmentosa (RP; MIM #268000) affects 1 in 3,000 to 5,000 people worldwide. It is one of the most common forms of inherited retinal degenerations 1 . RP typically starts with night blindness during the first two decades of life and progresses gradually to tunnel vision and eventual complete blindness in some patients. These clinical manifestations result from progressive dysfunction and death of rod photoreceptors followed by cone photoreceptors throughout the retina. The clinical features of RP are highly variable and may overlap with other inherited retinal degenerations, such as cone-rod dystrophy (CRD), Leber congenital amaurosis, and Usher syndrome. In addition to the clinical heterogeneity, the genetic etiologies of RP are also complex. RP may present various modes of inheritance including autosomal dominant, autosomal recessive, X-linked and digenic in rare cases 1 . To date, mutations in at least 80 genes have been associated with RP (RetNet, ). Therefore, accurate molecular diagnosis of RP patients is challenging but essential for better patient management and personalized treatment. In recent years, a number of studies have applied next-generation sequencing to understand the molecular basis of human Mendelian disorders including RP 2-4 . Specifically, customized target capture sequencing was used to screen mutations in known disease-causing genes with high efficiency. By this method, novel disease-causing alleles as well as genotype-phenotype correlations have been identified, leading to a substantial enhancement of our understanding of allele pathogenicity, protein function and population genetics. Hence, NGS-based molecular diagnosis has been proven as a robust approach for assessing Mendelian disease on a molecular level. Hispanic Americans are residents of the United States (US) descending from Latin America countries or Iberian peninsula 5 . They account for 17% of US population and represent a fast-growing ethnic group 6 , highlighting a need for understanding the molecular basis of genetic disorders. However, the mutation spectrum of RP in this population has not been evaluated before except in isolated cases. We collected 35 unrelated Hispanic RP probands from the Miami area and performed next-generation sequencing-based mutation screening using a
Australasian Plant Disease Notes
Resistant cucurbit rootstocks provided an effective control measure for Fusarium wilt of watermel... more Resistant cucurbit rootstocks provided an effective control measure for Fusarium wilt of watermelon caused by Fusarium oxysporum f. sp. niveum in Nghe An province, Vietnam. The hybrid cultivar, Bulrojangsaeng (Lagenaria siceraria) was the most suitable rootstock on all criteria but the seed is expensive. Therefore, the local Bau trang cultivar (L. siceraria) was adopted by farmers as the preferred rootstock on the basis of the low-cost seed. The grafting process is described and illustrated.
Stability investigations of isotropic and anisotropic exponential inflation in the Starobinsky–Bel–Robinson gravity
International Journal of Modern Physics D
In this paper, we would like to examine whether a novel Starobinsky–Bel–Robinson (SBR) gravity mo... more In this paper, we would like to examine whether a novel Starobinsky–Bel–Robinson (SBR) gravity model admits stable exponential inflationary solutions with or without spatial anisotropies. As a result, we are able to derive an exact de Sitter inflationary to this SBR model. Furthermore, we observe that an exact Bianchi type I inflationary solution does not exist in the SBR model. However, we find that a modified SBR model, in which the sign of coefficient of [Formula: see text] term is flipped from positive to negative, can admit the corresponding Bianchi type I inflationary solution. Unfortunately, stability analysis using the dynamical system approach indicates that both of these inflationary solutions turn out to be unstable. Interestingly, we show that a stable de Sitter inflationary solution can be obtained in the modified SBR gravity.
arXiv (Cornell University), Jul 13, 2021
We propose a novel k-Gauss-Bonnet model, in which a kinetic term of scalar field is allowed to no... more We propose a novel k-Gauss-Bonnet model, in which a kinetic term of scalar field is allowed to non-minimally couple to the Gauss-Bonnet topological invariant in the absence of a potential of scalar field. As a result, this model is shown to admit an isotropic power-law inflation provided that the scalar field is phantom. Furthermore, stability analysis based on the dynamical system method is performed to indicate that this inflation solution is indeed stable and attractive. More interestingly, a gradient instability in tensor perturbations is shown to disappear in this model.
General working characteristics of magnetocaloric materials in high magnetic fields
2017 IEEE International Magnetics Conference (INTERMAG), 2017
A big interest is attracted to the application of materials with a large magnetocaloric effect (M... more A big interest is attracted to the application of materials with a large magnetocaloric effect (MCE) at magnetic and magnetostructural phase transitions (PT) for creation of household refrigerators, operating near room temperature.
The European Physical Journal C, 2021
In this paper, we study a non-canonical extension of a supergravity-motivated model acting as a v... more In this paper, we study a non-canonical extension of a supergravity-motivated model acting as a vivid counterexample to the cosmic no-hair conjecture due to its unusual coupling between scalar and electromagnetic fields. In particular, a canonical scalar field is replaced by the string-inspired Dirac–Born–Infeld one in this extension. As a result, exact anisotropic inflationary solutions for this Dirac–Born–Infeld model are figured out under a constant-roll condition. Furthermore, numerical calculations are performed to verify that these anisotropic constant-roll solutions are indeed attractive during their inflationary phase.
Soil Science and Plant Nutrition, 2020
In-situ sorbent amendment is a relatively low-cost, low-impact approach for remediation of soil c... more In-situ sorbent amendment is a relatively low-cost, low-impact approach for remediation of soil contaminated with heavy metals (HMs), and thus is considered a way to be favored in developing countries. In this study, materials of non-hazardous, alkaline agronomic and industrial by-products were used as sorbents to explore their capacity of in situ immobilization of multiple HMs in mining-impacted arable soil. These sorbents included fly ash (FA), biochar (BC) and apatite (AP) and they were implemented with varying ratios of combinations. Results of soil microcosm tests showed that after incubation for 90 days, concentrations of Pb, Zn, and Cd in their exchangeable forms determined by a sequential extraction method significantly decreased in amended soils, as opposed to the unamended control. Of the five sets of amendments, the composite of FA, BC, and AP resulted in the maximum reduction (up to 80%) in the mobility of Pb, Zn, and Cd in soils. The mechanisms underlying the immobilization of HMs in amended soils might involve processes of surface precipitation, ion exchange and complexation, in which the physicochemical properties of sorbent materials played an important role. The immobilization efficacy of sorbent amendments on HMs in soil was further supported by pot experiments in which significant inhibition of HM accumulation in the belowground and aboveground tissues of maize was observed after 50-day cultivation in amended soils as compared with control soil. Together, these results suggest that the application of cost-saving and environmentally friendly materials derived from wastes as sorbents to remediate soils contaminated with multiple HMs is promising for developing countries like Vietnam.
EPJ Web of Conferences, 2018
In this work, Pr 2-x Nd x Fe 17 (x = 0 -2) ribbons with thickness of about 15 µm were prepared by... more In this work, Pr 2-x Nd x Fe 17 (x = 0 -2) ribbons with thickness of about 15 µm were prepared by melt-spinning method. The alloy ribbons were then annealed at different temperatures (900 -1100 o C) for various time (0.25 -2 h). The formation of the (Pr,Nd) 2 Fe 17 (2:17) crystalline phase in the alloys strongly depends on the Pr/Nd ratio and annealing conditions. Annealing time for the completed formation of the 2:17 phase in the rapidly quenched ribbons is greatly reduced in comparison with that of bulk alloys. Curie temperature, T C , of the alloys can be controlled in room temperature region by changing Pr/Nd ratio. Maximum magnetic entropy change (|∆S m | max ) and full width at haft the maximum peak (FWHM) of the magnetic entropy change of the alloys were respectively found to be larger than 1.5 J.kg -1 K -1 and 40 K in room temperature region with magetic field change ΔH = 12 kOe.
EPJ Web of Conferences, 2018
In this paper, we investigated the influence of additional compounds of Dy-Nb-Al, Nd-Cu-Al… on th... more In this paper, we investigated the influence of additional compounds of Dy-Nb-Al, Nd-Cu-Al… on the coercivity of the sintered Nd16.5Fe77B6.5 magnets. The additional compounds were first prepared by arc-melting method and then ground into particles with size in the range of 40 - 80 nm using a high energy ball milling method. After that, the additional powder were mixed with micrometer Nd-Fe-B powder before magnetic anisotropic pressing, vacuum sintering and annealing. The structure of the magnets was thoroughly analyzed using X-ray diffraction and electron microscopy techniques. The magnetic properties of the magnets were investigated on a pulsed field magnetometer. The results show that the coercivity of the sintered Nd-Fe-B magnets can be improved by introducing additional nanoparticles to their grain boundaries. The improvement of the coercivity of the magnets is clearly dependent on composition and fraction of the additional compounds. The coercivity has been enhanced 40% for the...
PLoS ONE, 2013
Thy-1 is a cell surface protein that is expressed during the differentiation of retinal ganglion ... more Thy-1 is a cell surface protein that is expressed during the differentiation of retinal ganglion cells (RGCs). Optic nerve injury induces progressive loss in the number of RGCs expressing Thy-1. The rate of this loss is fastest during the first week after optic nerve injury and slower in subsequent weeks. This study was undertaken to determine whether oral treatment with a water-soluble N-hydroxy-2,2,6,6-tetramethylpiperidine derivative (OT-440) protects against loss of Thy-1 promoter activation following optic nerve crush and whether this effect targets the earlier quick phase or the later slow phase. The retina of mice expressing cyan fluorescent protein under control of the Thy-1 promoter (Thy1-CFP mice) was imaged using a blue-light confocal scanning laser ophthalmoscope (bCSLO). These mice then received oral OT-440 prepared in cream cheese or dissolved in water, or plain vehicle, for two weeks and were imaged again prior to unilateral optic nerve crush. Treatments and weekly imaging continued for four more weeks. Fluorescent neurons were counted in the same defined retinal areas imaged at each time point in a masked fashion. When the counts at each time point were directly compared, the numbers of fluorescent cells at each time point were greater in the animals that received OT-440 in cream cheese by 8%, 27%, 52% and 60% than in corresponding control animals at 1, 2, 3 and 4 weeks after optic nerve crush. Similar results were obtained when the vehicle was water. Rate analysis indicated the protective effect of OT-440 was greatest during the first two weeks and was maintained in the second two weeks after crush for both the cream cheese vehicle study and water vehicle study. Because most of the fluorescent cells detected by bCSLO are RGCs, these findings suggest that oral OT-440 can either protect against or delay early degenerative responses occurring in RGCs following optic nerve injury.
Journal of Cancer Education, 2012
BACKGROUND-This study investigated missing data in a large cancer dataset, to alert educators to ... more BACKGROUND-This study investigated missing data in a large cancer dataset, to alert educators to the implications and limitations of missing data. The authors examined the California Cancer Registry for missing data by eight common cancer sites, seven sociodemographic and clinical variables, and the top three reporting sources. The gender variable had no missing data, followed by age (0.1% missing), ethnicity (2.2%), stage (7.0%), differentiation (36.3%), and birthplace (42.5%). Hospitals'/clinics' reports had the lowest percentages of missing data. CONCLUSIONS-Educators should anticipate the limitations of missing data in large datasets to prevent methodological flaws and misinterpretations of research findings.
Journal of Cancer Education, 2010
The USA seeks to eliminate health disparities by stimulating the rapid uptake of health-promoting... more The USA seeks to eliminate health disparities by stimulating the rapid uptake of health-promoting behaviors within disadvantaged communities. A health journalism internship incorporates social marketing strategies to increase communities' access to cancer information, while helping the interns who are recruited from underrepresented communities gain admission to top graduate schools. Interns are taught basic health journalism skills that enable them to create immediate streams of cancer-related press releases for submission to community newspapers. Interns are charged with the social responsibility of continuing this dissemination process throughout their careers. Intermediate outcomes are measured as mediators of distal behavioral change goals.
Investigative Opthalmology & Visual Science, 2011
To investigate how OPA1 expression and distribution are altered by increased nitric oxide (NO) an... more To investigate how OPA1 expression and distribution are altered by increased nitric oxide (NO) and whether aminoguanidine, a relative selective NO synthase (NOS)-2 inhibitor, can restore OPA1 expression and subsequently increase retinal ganglion cell (RGC) survival in ocular hypertensive rats. METHODS. Elevated intraocular pressure was induced unilaterally by translimbal laser photocoagulation of the trabecular meshwork in Sprague-Dawley rats. Aminoguanidine (100 mg/ kg) was administered by intraperitoneal injection for 3 consecutive days in rats after laser treatment. Preservation of fluorochrome-labeled RGCs was assessed 2 weeks later. GFAP, NOS-2, or OPA1 protein expression and distribution were assessed by Western blot analysis and immunohistochemistry. OPA1 mRNA was measured by qPCR. RESULTS. OPA1 mRNA and protein expression were significantly increased in the vehicle-treated hypertensive rat retina. Aminoguanidine treatment significantly reduced expression of the 90-and 65-kDa OPA1 isoforms but did not significantly change the 80-kDa OPA1 isoform in hypertensive retina. In addition, the increases in NOS-2 and GFAP protein expression were blocked by aminoguanidine treatment in the hypertensive retina. NOS-2 immunoreactivity was induced in cells of the ganglion cell layer in the vehicle-treated hypertensive retina. Aminoguanidine treatment significantly increased RGC survival at 2 weeks after IOP elevation. CONCLUSIONS. Although NOS-2/NO induction may contribute to hypertensive retinal cell death, an increase in mitochondrial OPA1 may provide an important cellular defense mechanism against pressure-mediated retinal damage. These findings suggest that mitochondrial preservation after inhibition of NOS-2 may be useful for protecting RGCs against glaucomatous damage. (Invest
Investigative Opthalmology & Visual Science, 2011
To determine whether acute intraocular pressure (IOP) elevation alters dynamin-related protein 1 ... more To determine whether acute intraocular pressure (IOP) elevation alters dynamin-related protein 1 (Drp1) as well as whether a selective inhibitor of Drp1, mdivi-1, can block apoptotic cell death and subsequently increase retinal ganglion cell (RGC) survival in ischemic mouse retina. METHODS. C57BL/6 mice received injections of mdivi-1 (50 mg/kg) or vehicle, and then transient retinal ischemia was induced by acute IOP elevation. RGC survival was measured after FluoroGold labeling. Drp1 and glial fibrillary acidic protein (GFAP) protein expression and distribution were assessed at 12 hours after ischemia-reperfusion by Western blot and immunohistochemistry. Apoptotic cell death was assessed by TUNEL staining. RESULTS. Drp1 and GFAP protein expression was significantly increased in the early neurodegenerative events (within 12 hours) of ischemic mouse retina. Mdivi-1 treatment blocked apoptotic cell death in ischemic retina, and significantly increased RGC survival at 2 weeks after ischemia. In the normal mouse retina, Drp1 is expressed in the ganglion cell layer (GCL) as well as the inner plexiform layer, the inner nuclear layer (INL), and the outer plexiform layer (OPL). In the GCL, Drp1 immunoreactivity was strong in RGCs. While Drp1 protein expression was increased in the GCL of vehicle-treated ischemic retina at 12 hours. Mdivi-1 treatment did not change this increase of Drp1 protein expression but significantly decreased GFAP protein expression. CONCLUSIONS. These findings suggest that altered Drp1 activity after acute IOP elevation may be an important component of a biochemical cascade leading to RGC death in ischemic retina.
Cell death & disease, 2011
Glutamate excitotoxicity leads to fragmented mitochondria in neurodegenerative diseases, mediated... more Glutamate excitotoxicity leads to fragmented mitochondria in neurodegenerative diseases, mediated by nitric oxide and S-nitrosylation of dynamin-related protein 1, a mitochondrial outer membrane fission protein. Optic atrophy gene 1 (OPA1) is an inner membrane protein important for mitochondrial fusion. Autosomal dominant optic atrophy (ADOA), caused by mutations in OPA1, is a neurodegenerative disease affecting mainly retinal ganglion cells (RGCs). Here, we showed that OPA1 deficiency in an ADOA model influences N-methyl-D-aspartate (NMDA) receptor expression, which is involved in glutamate excitotoxicity and oxidative stress. Opa1(enu/+) mice show a slow progressive loss of RGCs, activation of astroglia and microglia, and pronounced mitochondrial fission in optic nerve heads as found by electron tomography. Expression of NMDA receptors (NR1, 2A, and 2B) in the retina of Opa1(enu/+) mice was significantly increased as determined by western blot and immunohistochemistry. Superoxide ...
Australasian Plant Disease Notes, 2009
Fusarium wilt of watermelon caused by Fusarium oxysporum f. sp. niveum caused seedling losses in ... more Fusarium wilt of watermelon caused by Fusarium oxysporum f. sp. niveum caused seedling losses in nurseries, as well as severe losses in many crops in Nghe An province, Vietnam, in 2008. Isolates of the fungus were shown to be pathogenic. All 20 cultivars grown in the province in 2008 were susceptible. This is the first formal report of this disease in Vietnam.
ACS omega, Jan 30, 2017
Self-organized bacteria have been the subject of interest for a number of applications, including... more Self-organized bacteria have been the subject of interest for a number of applications, including the construction of microbial fuel cells. In this paper, we describe the formation of a self-organized, three-dimensional network that is constructed using B-1280 cells in a hydrogel consisting of poly(vinyl alcohol) (PVA) with -vinyl pyrrolidone (VP) as a cross-linker, in which the bacterial cells are organized in a particular side-by-side alignment. We demonstrated that nonmotile cells are able to reorganize themselves, transforming and utilizing PVA-VP polymeric networks through the molecular interactions of bacterial extracellular polysaccharide (EPS) components such as acetan, cellulose, dextran, and levan. Molecular dynamics simulations of the EPS components interacting with the hydrogel polymeric network showed that the solvent-exposed loops of PVA-VP extended and engaged in bacterial self-encapsulation.
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Papers by Duy Hiệp Nguyễn