Publications by authors named "Christopher Seto"

Biweekly county COVID-19 data were linked with Longitudinal Employer-Household Dynamics data to analyze population risk exposures enabled by pre-pandemic, country-wide commuter networks. Results from fixed-effects, spatial, and computational statistical approaches showed that commuting network exposure to COVID-19 predicted an area's COVID-19 cases and deaths, indicating spillovers. Commuting spillovers between counties were independent from geographic contiguity, pandemic-time mobility, or social media ties.

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Objective: Risk assessment and response is important for understanding human behavior. The divisive context surrounding the coronavirus pandemic inspires our exploration of risk perceptions and the polarization of mitigation practices (i.e.

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Purpose: The purpose of the study was to identify proximal links between electronic cigarette (e-cigarette) use and numerous indicators of adjustment, delinquency, and other substance use in adolescence, beyond prior levels and confounders.

Methods: The ongoing Millennium Cohort Study is a nationally representative, intergenerational, longitudinal study of children born 2000-2001 in the United Kingdom followed from birth to age 14 years (n = 11,564 adolescents and their parents). A series of ordinary least squares and logistic regressions compared 14-year-old e-cigarette only users to never users and to combustible/dual users on 10 measures of adjustment (school engagement, well-being, and self-esteem), delinquency (theft, vandalism, disorderly conduct, and graffitiing), and other substance use (frequent alcohol use, heavy drinking, and marijuana use).

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Self-assembly of nanoparticles (NPs) is at the heart of nanotechnology, and has shown many potential applications in fabricating nanodevices with highly controlled functionality. Two-dimensional (2D) arrays of NPs can provide a thin and uniform NP array with each NP being exposed on the surface to maximize NP catalysis. This minireview summarizes the recent progress on the fabrication and application of 2D NP arrays.

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Parasites have developed a variety of strategies for invading hosts and escaping their immune response. A common mechanism by which parasites escape nitric oxide (NO) toxicity is the activation of host arginase. This activation leads to a depletion of l-arginine, which is the substrate for NO synthase, resulting in lower levels of NO and increased production of polyamines that are necessary for parasite growth and differentiation.

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Ni Pd nanoparticles supported on nitrogen-doped graphene (NG) acts as a catalyst for the hydrodehalogenation of halogenated aromatics under mild reaction conditions. It reduces mono- or dichloroarenes to the corresponding dehalogenated arenes in >90 % yield in 10 % aqueous isopropanol solvent at or below 50 °C within 5 h. Tests on a variety of substrates containing various functional groups show that the catalyst is selective for reduction of C-Cl and C-Br bonds.

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We report a facile method for assembly of a monolayer array of nitrogen-doped graphene (NG) and nanoparticles (NPs) and the subsequent transfer of two layers onto a solid substrate (S). Using 3 nm NiPd NPs as an example, we demonstrate that NiPd-NG-Si (Si=silicon wafer) can function as a catalyst and show maximum NiPd catalysis for the hydrolysis of ammonia borane (H NBH , AB) with a turnover frequency (TOF) of 4896.8 h and an activation energy (E ) of 18.

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We report a seed-mediated growth of 2.3 nm AgPd nanoparticles (NPs) in the presence of 40 × 5 nm WO nanorods (NRs) for the synthesis of AgPd/WO composites. The strong interactions between AgPd NPs and WO NRs make the composites, especially the AgPd/WO, catalytically active for dehydrogenation of formic acid (TOF = 1718 h and E = 31 kJ/mol) and one-pot reactions of formic acid, 2-nitrophenol, and aldehydes into benzoxazoles in near quantitative yields under mild conditions.

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The objective of the present study was to determine the in-vitro effect of Abietyl-Isothiocyanate (ABITC), a representative of a new class of anti-cancer drugs, on endometrial cancer (EC) cell lines. ABITC at concentrations ≥1 μM displayed dose-dependent and selective cytotoxicity to EC cell lines (ECC-1, AN3CA, RL95-2) in comparison to other cancer cell lines. After treatment with ABITC, ECC-1 unlike control cells displayed hallmark features of apoptosis including chromatin condensation and nuclear fragmentation.

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A kinetic analysis of an enzyme assay employing a synthetic substrate that produces a detectable signal through a spontaneous organic cyclization/elimination reaction following the enzymatic reaction was conducted. The results from the calculation were used to predict the lag period and provide accurate measurements of the activity of alkaline phosphatase using the fluorogenic substrate (1).

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Protein tyrosine phosphatases such as PTP1B and YopH are potential targets for the development of therapeutic agents against a variety of pathological conditions including diabetes, obesity, and infection by the bacterium Yersinia pestis. A focused library of bidentate α-ketoacid-based inhibitors has been screened against several tyrosine phosphatases. Compound 2a has IC(50) values of 43 and 220 nM against YopH and PTP1B, respectively, and shows a 30-fold selectivity for PTP1B over the closely related phosphatase TCPTP.

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Three novel metal squaric acid-peptide complexes, SQI-SQIII were prepared by addition of indium triflate or zinc chloride to the previously reported compounds [1], 3-(hydroxymethylamino)-4-(l-isoleucine methyl ester)-3-cyclobutene-1,2-dione (squarate 1), and 3-(hydroxymethylamino)-2-(l-isoleucine methyl ester)-4-thioxo-2-cyclobuten-1-one (squarate 2). The structures of SQI-SQIII were elucidated using NMR analysis. The electrochemical applications of two of these metal-squaric acid systems (SQI and SQII) were also investigated.

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1-Aryltetrahydroisoquinolines (1-arylTHIQs) are important structural motifs in many alkaloids and biologically active compounds. Ligand 2a promotes the enantioselective addition of arylzinc reagents to 3,4-dihydroisoquinoline N-oxide to yield (S)-1-arylTHIQs in 97-99% ee. Pinacol arylboronic esters are the optimal precursors for the arylzinc reagents.

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A new fluorescent assay for Ser/Thr protein phosphatases has been developed. Hydrolysis of a phosphoSer residue liberates the Ser hydroxyl group, which induces a cyclization reaction on the N-terminal carbamate and releases a fluorescent reporter. Sequence selectivity is observed using several peptide substrates against alkaline phosphatase (ALP), bacteriophage lambda protein phosphatase (lambda-PPase), and vaccinia H1 related phosphatase (VHR).

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Macrocyclic inhibitors for the serine protease plasmin were synthesized and evaluated. The inhibitors were constructed starting from a cyclohexanone core. This core was linked to either the C- or N-terminus of a peptide so that the inhibitors were designed to interact with the non-primed or primed binding sites of the protease.

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Gene duplications in rodents have given rise to a family of proteases that are expressed exclusively in placenta. To define the biological role of these enzymes specific inhibitors are needed to differentiate their activities from other more ubiquitously expressed proteases, such as cathepsins B and L. Libraries of peptidyl inhibitors based upon a 4-cyclohexanone pharmacophore were screened for inhibition of cathepsins P, L, and B.

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Protein tyrosine phosphatases (PTPs) are important regulators of signal transduction pathways. Potent and selective PTP inhibitors are useful for probing these pathways and also may serve as drugs for the treatment of a variety of diseases including type 2 diabetes and infection by the bacterium Yersinia pestis. In this report Cu(I)-catalyzed 'click' cycloaddition reactions between azides and alkynes were employed to generate two sequential libraries of PTP inhibitors.

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Three series of cyclic ketone inhibitors were synthesized and evaluated against the serine protease plasmin. Peptide inhibitors that incorporated 3-oxotetrahydrofuran and 3-oxotetrahydrothiophene 1,1-dioxide groups had the highest activities. Alkylamino substituents, which were designed to bind in the S1 subsite of plasmin, were attached to the inhibitors.

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Ligand 2a promotes the enantioselective addition of vinylzinc reagents to 3,4-dihydroisoquinoline N-oxide to yield chiral allylic hydroxylamines. With 0.1 equiv of the ligand, the product is obtained in up to 84% ee, whereas with 1.

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[structure: see text] A series of squaric acid-peptide conjugates were synthesized and evaluated as inhibitors of MMP-1. The cyclobut-3-enedione core was substituted at the 3-position with several functional groups, such as -N(alkyl)OH, -NHOH, and -OH, that are designed to bind to the zinc atom in the active site of the metalloprotease. The 4-position of the cyclobut-3-enedione was derivatized with mono- or dipeptides that are designed to bind in the S1' and S2' subsites of the enzyme, and position the metal chelating group appropriately in the active site for binding to zinc.

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A combinatorial library of 400 serine protease inhibitors with the general structure Cbz-X(aa)-Trp-cyclohexanone-Trp-Y(aa)-OH has been constructed. The library was synthesized on the solid phase using mix-and-split synthesis, where 20 different amino acids were incorporated at both the X(aa) and Y(aa) positions. These two positions correspond to the S3 and S3' subsites of the active site.

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[reaction: see text] A series of N-acylethylenediamine-based ligands were synthesized from Boc-protected amino acids. The ligands were screened for the ability to catalyze the asymmetric addition of vinylzinc reagents to aldehydes. Three sites of diversity on the ligands were optimized for this reaction using a positional scanning approach.

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[reaction: see text] The enantiomeric excess of methyl p-tolyl sulfoxide can be determined in a high throughput format by measuring its ability to inhibit the alcohol dehydrogenase catalyzed oxidation of ethanol. The two enantiomers of the sulfoxide have very different inhibition constants for the enzyme. Thus, the initial rate of ethanol oxidation in the presence of the sulfoxide is correlated with the sulfoxide enantiomeric excess.

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The plasminogen system is important in the proteolytic cascade that facilitates angiogenesis, a process that is essential for tumor growth and metastasis. The serine protease plasmin has a central role in the plasminogen system. This protease acts by degrading several components of the basement membrane and by activating other proteases.

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