John Nguyen - Academia.edu (original) (raw)

Papers by John Nguyen

Journal of Ophthalmic Inflammation and Infection, 2015

Background Granulicatella adiacens, a recent taxonomic addition, is a commensal organism of the o... more Background Granulicatella adiacens, a recent taxonomic addition, is a commensal organism of the oral, gastrointestinal, and urogenital tracts and is rarely encountered in the orbit and eye. Findings We present a 46-year-old Caucasian woman with chronic dacryocystitis who underwent an external dacryocystorhinostomy and was found to have G. adiacens. Conclusions This is an unusual causative organism isolated in the nasolacrimal system and, to our knowledge, the first reported case of chronic dacryocystitis associated with G. adiacens.

Proceedings : a conference of the American Medical Informatics Association / ... AMIA Annual Fall Symposium. AMIA Fall Symposium, 1997

To meet the data-processing requirements for protocol-based decision support, a clinical data-man... more To meet the data-processing requirements for protocol-based decision support, a clinical data-management system must be capable of creating high-level summaries of time-oriented patient data, and of retrieving those summaries in a temporally meaningful fashion. We previously described a temporal-abstraction module (RESUME) and a temporal-querying module (Chronus) that can be used together to perform these tasks. These modules had to be coordinated by individual applications, however, to resolve the temporal queries of protocol planners. In this paper, we present a new module that integrates the previous two modules and that provides for their coordination automatically. The new module can be used as a standalone system for retrieving both primitive and abstracted time-oriented data, or can be embedded in a larger computational framework for protocol-based reasoning.

Protein Expression and Purification, 2010

The Escherichia coli maltose binding protein (MBP) has been utilized as a translational fusion pa... more The Escherichia coli maltose binding protein (MBP) has been utilized as a translational fusion partner to improve the expression of foreign proteins made in E. coli. When located N-terminal to its cargo protein, MBP increases the solubility of intracellular proteins and improves the export of secreted proteins in bacterial systems. We initially explored whether MBP would have the same effect in the methylotrophic yeast Pichia pastoris, a popular eukaryotic host for heterologous protein expression. When MBP was fused as an N-terminal partner to several C-terminal cargo proteins expressed in this yeast, proteolysis occurred between the two peptides, and MBP reached the extracellular region unattached to its cargo. However, in two of three instances, the cargo protein reached the extracellular region as well, and its initial attachment to MBP enhanced its secretion from the cell. Extensive mutagenesis of the spacer region between MBP and its C-terminal cargo protein could not inhibit the cleavage although it did cause changes in the protease target sites in the fusion proteins, as determined by mass spectrometry. Taken together, these results suggested that an uncharacterized P. pastoris protease attacked at different locations in the region C-terminal of the MBP domain, including the spacer and cargo regions, but the MBP domain could still act to enhance the secretion of certain cargo proteins.

The Journal of Pediatrics, 2010

From the Department of Ophthalmology, HarvardMedical School, Boston, MA (A.F.); Ophthalmic Plasti... more From the Department of Ophthalmology, HarvardMedical School, Boston, MA (A.F.); Ophthalmic Plastic and Reconstructive Surgery Division, Massachusetts Eye & Ear ore than a decade of medical and surgical innovation has produced a substantial array of interventional alternatives in the treatment of vascular anomalies. Advances in diagnostics, anesthetics, lasers, pharmacology, and surgery allow us to hasten the resolution of infantile hemangiomas and improve ultimate outcomes. The long-standing recommendation of passive observation is outdated; patients and their families have many new alternatives that are safe, effective, and available. The 1980s yielded a diagnostic revolution in the field of vascular anomalies, and the 1990s illuminated the immunohistochemically based pathogenesis of infantile hemangiomas. Surely the 2000s will be known for interventional progress in this field. Optimal treatment of hemangiomas involves cooperation in several disciplines, which has been facilitated by multidisciplinary teams at some medical centers in the United States and abroad. Treatment goals still include preservation of life and sight, but outward appearance, psychosocial health, and family dynamics must also be considered. In most instances now, some combination of interventions can indeed improve outcome. The initial decision to treat depends largely on location and size of the lesion, patient age, systemic involvement, and family desire. Developing a case-specific interventional strategy must consider, in addition to these factors, the subtype, stage, and depth of the hemangioma.We present a rationale for treatment selection and review emerging therapies available for patients with infantile hemangiomas.

Genomics, 1991

We have used DNA polymorphisms detected by probes for 1 lq to order 16 genes and to determine the... more We have used DNA polymorphisms detected by probes for 1 lq to order 16 genes and to determine the genetic distances between them. Our map includes the genes for CD20, tyrosinase, progesterone receptor, stromelysin, collagenase, N-CAM, dopamine-D, receptor, apolipoproteins AI-CIII-AIV, CD3-c,-6, and-7, porphobilinogen deaminase, thy-l, and ets-1. These genes have previously been sequenced as well as placed on the llq cytogenetic map, which now makes them anchor points between the cytogenetic, genetic, and physical maps of this region. The ordering and distances between these genes are of immediate use in testing hypotheses of candidate genes for human genetic diseases associated with chromosome llq. A comparison between our genetic map and similar maps from other species defines regions of homologous synteny that may he useful in mapping human genetic disease genes localized to the 1 lq region. Analysis of such homology provides additional bases for speculation of the evolutionary histories of gene families in this region.

Journal of the American …, 1993

Methods. We administered sequential intracoronary and aortic root injections (518 injections) of ... more Methods. We administered sequential intracoronary and aortic root injections (518 injections) of sonicated albumin in 25 closed chest normal dogs to measure the effectiveness and reproducibility of this product. Time-intensity curves, as a measure of myocardial ...

stand for the resonance multiplicity singlet, broad singlet, doublet, doublet of doublets, broad ... more stand for the resonance multiplicity singlet, broad singlet, doublet, doublet of doublets, broad doublet, doublet of doublet of doublets, triplet, quartet, broad quartet, quintet, multiplet and broad multiplet, respectively. IR spectra were recorded on an Avatar 360 FT-IR spectrometer. Mass spectra were recorded at the Mass Spectrometry Facility at the Department of Chemistry of the Boston University in Boston, MA on a Waters Q-Tof API-US with ESI high resolution mass spectrometer. Concentration refers to removal of solvent under reduced pressure (house vacuum at ca. 20 mmHg).

Herein, the development of visible light-mediated atom transfer radical addition (ATRA) of haloal... more Herein, the development of visible light-mediated atom transfer radical addition (ATRA) of haloalkanes onto alkenes and alkynes using the reductive and oxidative quenching of [Ir{dF(CF3)ppy}2(dtbbpy)]PF6 and Ru(bpy)3Cl2 is presented. Initial investigations indicated that the oxidative quenching of photocatalysts could effectively be utilized for ATRA, and since that report, the protocol has been expanded by broadening the scope of the reaction in terms of the photocatalysts, substrates, and solvents. In addition, further modifications of the reaction conditions allowed for the efficient ATRA of perfluoroalkyl iodides onto alkenes and alkynes utilizing the reductive quenching cycle of Ru(bpy)3Cl2 with sodium ascorbate as the sacrificial electron donor. These results signify the complementary nature of the oxidative and reductive quenching pathways of photocatalysts and the ability to predictably direct reaction outcome through modification of the reaction conditions.

Atom transfer radical addition of haloalkanes and α-halocarbonyls to olefins is efficiently perfo... more Atom transfer radical addition of haloalkanes and α-halocarbonyls to olefins is efficiently performed with the photocatalyst Ir[(dF(CF 3)ppy) 2 (dtbbpy)]PF 6. This protocol is characterized by excellent yields, mild conditions, low catalyst loading, and broad scope. In addition, the atom transfer protocol can be used to quickly and efficiently introduce vinyl trifluoromethyl groups to olefins and access 1,1-cyclopropane diesters. Atom transfer radical addition (ATRA) of haloalkanes and α-halocarbonyls to olefins serves as an atom-economical 1 method of simultaneously forming CC and C-X bonds. Following Kharasch's seminal work, 2 Curran, 3 Oshima, 4 and others have developed ATRA into a useful tool in organic chemistry. However, typical ATRA initiators include toxic and hazardous reagents, such as peroxides, 2 organotin reagents, 3 and triethylboron. 4 Other less common initiators have also been used, including p-methoxybenzene-diazonium tetraflouroborate with TiCl 3 , 5 dimanganese decacarbonyl, 6 copper, 7 iron, 8 bimetallic Rh-Ru complexes, 9 and chromium(II) acetate, 10 but these methods employ harsh conditions and/or lack broad functional group tolerance. In this regard, we sought to develop a protocol capable of effecting ATRA with a broad scope under mild conditions and utilizing safer reagents using photoredox catalysis (Figure 1). 11

International journal of …, 2006

Groups did not differ in age, gender or EF. Group III patients had larger LAD (4.6 + − 1.0 cm) co... more Groups did not differ in age, gender or EF. Group III patients had larger LAD (4.6 + − 1.0 cm) compared with both Group I (3.7 ± 0.6) and Group II (3.7 ± 0.5 cm) (p < 0.0001). A markedly enlarged (arbitrarily defined as LAD higher or equal 5 cm) had an odds ratio of 34 (95% CI 8144) ...

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This study protocol was approved by the Institutional Review Board of the Baylor College of Medic... more This study protocol was approved by the Institutional Review Board of the Baylor College of Medicine. Consecutive patients referred to the cardiac catheterization laboratory for coronary angiography for clinical reasons were approached for recruitment. After informed consent, ...

Journal of the American …, 2010

Of the 122 patients studied (mean age, 55 ± 9 years; mean LVEF, 61 ± 6%), 67 (55%) were women, 10... more Of the 122 patients studied (mean age, 55 ± 9 years; mean LVEF, 61 ± 6%), 67 (55%) were women, 108 (88%) had hypertension, and 79 (65%) had significant coronary artery disease at catheterization. E/e′ was significantly correlated with pre-A (R = 0.63, P < .0001) ...

American Journal of Ophthalmology, 2009

American Journal of Obstetrics and Gynecology, 2006

American Journal of Obstetrics and Gynecology, 2005

We measured the levels of interleukin-18 (IL-18), soluble Fas (sFas) and Fas ligand (sFasL) to as... more We measured the levels of interleukin-18 (IL-18), soluble Fas (sFas) and Fas ligand (sFasL) to assess whether IL-18-mediated apoptosis is involved in intraamniotic infection. STUDY DESIGN: Amniocentesis was performed on 81 singleton pregnant women with preterm contractions, labor, or rupture of membranes. Twentyfive patients had intraamniotic infection, and 56 did not. Intraamniotic infection was defined as the presence of a positive amniotic fluid culture. Amniotic fluid neutrophil counts were determined. Amniotic fluid levels of IL-18, sFas, and sFaL were measured by an enzyme-linked immunoassay. Student t test and Pearson correlation coefficient were used for statistical analyses. Data were expressed as mean G SEM. RESULTS: There were no significant differences in maternal age, gestational age, race or parity between two groups. Amniotic fluid mean levels of IL-18, sFas, and sFasL were significantly higher in pregnant women with intraamniotic infection than in those without intraamniotic infection (

American Journal of Obstetrics and Gynecology, 2009

OBJECTIVE: We sought to determine whether the Fas (Ϫ670) singlenucleotide polymorphism is associa... more OBJECTIVE: We sought to determine whether the Fas (Ϫ670) singlenucleotide polymorphism is associated with intrauterine growth restriction. STUDY DESIGN: Twenty-seven pregnant women with intrauterine growth restriction in the absence of preeclampsia and 50 pregnant women with uncomplicated pregnancies were studied. DNA was extracted from maternal and infant buccal smears and allelic discrimination was performed for Fas (Ϫ670). Student t test, 2 , and z tests were used. RESULTS: There were no differences in maternal age, race, or parity between the intrauterine growth restriction and control patients. Mothers of intrauterine growth restriction infants had a significantly different genotype distribution for this single nucleotide polymorphism, and for the ratio of GG genotype (GG, AA: 0.41, 0.18 maternal intrauterine growth restriction; 0.14, 0.32 controls; respectively, P ϭ .03). These genotype differences were significantly different in white, but not black mothers with intrauterine growth restriction (P ϭ .03, and .3; respectively). In contrast, no differences were found in infants' Fas (Ϫ670) single-nucleotide polymorphism genotypes. CONCLUSION: This study demonstrates an association between the maternal Fas (Ϫ670) single-nucleotide polymorphism and the development of intrauterine growth restriction.