Publications by authors named "Stephanie Contreras"

Background: Neisseria gonorrhoeae (Ng) causes the sexually transmitted disease gonorrhoea. There are no vaccines and infections are treated principally with antibiotics. However, gonococci rapidly develop resistance to every antibiotic class used and there is a need for developing new antimicrobial treatments.

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Newcomer Latinx immigrant youths in the United States are currently in a syndemic of increased risk of behavioral health concerns, disparities in access to related services, and are disproportionately impacted by the COVID-19 pandemic. This study used qualitative inquiry to examine the impact that the transition to telehealth had on a school-based group prevention program for immigrant youth, Fuerte, within the context of this syndemic. Data included semi-structured interviews with group leaders, and focus groups with youth program participants.

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The current study uplifts the efforts of community-based college access and success programs (CAS) to support the college preparation, matriculation, and persistence of underserved students during COVID-19. Fifty-eight CAS across the United States completed an online survey that gathered information about organizational demographics, COVID-19 challenges, responses to challenges, and communication with constituents and funding needs during COVID-19. Results suggested CAS faced multiple challenges due to COVID-19 that affected the organization, staff, and constituents.

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Accurate prediction and modeling of an enzyme's active site are critical for engineering efforts as well as providing insight into an enzyme's naturally occurring function. Previous efforts demonstrated that the integration of constraints enforcing strict geometric orientations between catalytic residues significantly improved the modeling accuracy for the active sites of monomeric enzymes. In this study, a similar approach was explored to evaluate the effect on the active sites of homomeric enzymes.

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An engineered reversal of the β-oxidation cycle (r-BOX) and the fatty acid biosynthesis (FAB) pathway are promising biological platforms for advanced fuel and chemical production in part due to their iterative nature supporting the synthesis of various chain length products. While diverging in their carbon-carbon elongation reaction mechanism, iterative operation of each pathway relies on common chemical conversions (reduction, dehydration, and reduction) differing only in the attached moiety (acyl carrier protein (ACP) in FAB vs Coenzyme A in r-BOX). Given this similarity, we sought to determine whether FAB enzymes can be used in the context of r-BOX as a means of expanding available r-BOX components with a ubiquitous set of well characterized enzymes.

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An empirically observed correlation between ion mobility cross sections in helium and nitrogen buffer gases was examined as a function of temperature, molecular size, and shape. Experimental cross sections were determined for tetraglycine, bradykinin, angiotensin 2, melittin, and ubiquitin at 300 K and in the range from 80 to 550 K on home-built instruments and calculated by the projection superposition approximation (PSA) method. The PSA was also used to predict cross sections for larger systems such as human pancreatic alpha-amylase, concanavalin, Pichia pastoris lysyl oxidase, and Klebsiella pneumoniae acetolactate synthase.

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A variety of proteases release hundreds of endogenous peptide fragments from intact bovine milk proteins. Mass spectrometry-based peptidomics allows for high throughput sequence assignment of a large number of these peptides. Mastitis is known to result in increased protease activity in the mammary gland.

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An extensive mass spectrometry analysis of the human milk peptidome has revealed almost 700 endogenous peptides from 30 different proteins. Two in-house computational tools were created and used to visualize and interpret the data through both alignment of the peptide quasi-molecular ion intensities and estimation of the differential enzyme participation. These results reveal that the endogenous proteolytic activity in the mammary gland is remarkably specific and well conserved.

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