38 results on '"Márquez-Magaña L"'
Search Results
2. CodY Is a Nutritional Repressor of Flagellar Gene Expression in Bacillus subtilis
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Bergara, F., primary, Ibarra, C., additional, Iwamasa, J., additional, Patarroyo, J. C., additional, Aguilera, R., additional, and Márquez-Magaña, L. M., additional
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- 2003
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3. Environmental Regulation of Bacillus subtilis ς D -Dependent Gene Expression
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Mirel, D. B., primary, Estacio, W. F., additional, Mathieu, M., additional, Olmsted, E., additional, Ramirez, J., additional, and Márquez-Magaña, L. M., additional
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- 2000
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4. Dual Promoters Are Responsible for Transcription Initiation of the fla/che Operon in Bacillus subtilis
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Estacio, W., primary, Anna-Arriola, S. Santa, additional, Adedipe, M., additional, and Márquez-Magaña, L. M., additional
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- 1998
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5. Regulation of sigma D expression and activity by spo0, abrB, and sin gene products in Bacillus subtilis
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Márquez-Magaña, L M, primary, Mirel, D B, additional, and Chamberlin, M J, additional
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- 1994
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6. Characterization of the sigD transcription unit of Bacillus subtilis
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Márquez-Magaña, L M, primary and Chamberlin, M J, additional
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- 1994
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7. Evaluation of a mentorship matchmaking event at an academic research institution to reinforce the scientific workforce pathway for underrepresented minority groups.
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Gutierrez S, Seuferer JA, Guerrero AM, Carrasco Y, Bibbins-Domingo K, Nguyen T, Márquez-Magaña L, Nystul T, and Morris MD
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- Humans, Female, Male, United States, Biomedical Research, Mentoring, Program Evaluation, Cultural Diversity, Career Choice, Adult, Mentors, Minority Groups statistics & numerical data
- Abstract
Background: Mentorship and research experiences are crucial for STEMM career entry and advancement. However, systemic barriers have excluded people from historically underrepresented groups., Methods: In 2021, a virtual "matchmaking event" was held to connect NIH-funded research mentors with historically underrepresented trainees and initiate mentored research experiences. Survey data collected over 12 months was analyzed to evaluate the program's success considering the number of mentor-trainee connections, mentor-trainee research experience matches, and NIH diversity supplement application status. Statistical tests, including student's t-test, ANCOVAs, and chi-square tests, evaluated differences between attendee groups and survey time points., Results: Out of 314 mentors contacted and 99 registered trainees, 113 mentors and 92 trainees participated. Among mentors (n = 73), 53% identified as women, 56% as non-Hispanic white, and a majority (81%) reported being the first in their family to attend college. Among trainees (n = 79), about two-thirds (67%) identified as women, 47% identified as Hispanic/Latinx, and 15% identified as Black/African American. Both mentors and trainees were extremely satisfied with the overall event (57% and 69%, respectively) and would recommend it to others (74% and 90%, respectively). Most mentor participants established at least one mentor-trainee connection after the event (n = 64, 57%), a mentor-trainee research experience match (n = 40, 35%), and planned to submit an NIH diversity supplement (n = 31, 27%). Many trainees obtained paid positions through the mentor-trainee research experience. One year after the event, 11 trainees secured NIH diversity supplement funding with their mentors., Conclusions: The matchmaking event began bridging a much-needed gap in the research pathway by creating opportunities for trainees to connect with mentors and obtain funded research opportunities., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. The University of California, San Francisco institutional review board approved both the study and the waiver of informed consent as this study was deemed exempt from human subjects’ research procedures (IRB #21-33387). Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)
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- 2025
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8. Investigating the Impacts of a Modified Mindfulness Practice on Minoritized College Students' Chronic Stress.
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Michaud M, Evans M, Mendez R, Zapanta J, Trochez A, Mehta KM, Márquez-Magaña L, and Parangan-Smith A
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Context: Students of color in the United States experience elevated stress across the entire spectrum of education, spanning from early stages of K-12 to the more advanced stages of postgraduate studies. This sustained state of chronic stress decreases learning and curtails opportunities, especially in science, technology, engineering, and math (ST EM) fields, where stress levels are considered exceptionally high. Mindfulness-based practices such as MBSR have a proven effective for stress reduction in college students. However, to date, mindfulness practices have yet to be designed to support the unique needs of minoritized students with intersectional identities (e.g., poor, English as second language learners, and sexual/gender minorities) that are stigmatized in ST EM., Objectives: This article describes the development of an online, eight-week modified mindfulness practice (MMP) for minoritized students adapted from traditional MBSR. The MMP was purposely designed to be culturally inclusive and anti-racist, with the goal to reduce stress in undergraduate students of color in ST EM., Methods: In this pilot study, we assessed the impact of MMP using both biological and perceived stress measures. Specifically, cortisol was measured from donated biospecimen hair samples, the Perceived Stress Scale measured perceived stress, and key informant interviews were conducted to understand student stressors and coping strategies before and after the intervention., Results: While the observed decrease biological and perceived stress before and after the intervention was not statistically significant due to the small sample size of this pilot study, we see a dramatic positive change in student coping strategies., Conclusion: This study highlights the importance of providing minoritized students with options for stress reduction that are relevant and accessible., (© The Author(s) 2024. Published by Mary Ann Liebert, Inc.)
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- 2024
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9. The Impact of Insider Researcher Trainees in Recruiting and Retaining Latinx in an Outdoor Health Promotion Research Study.
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Mendez R, Velazquez E, Gimenez A, Michaud M, Mendez J, Wong M, Quesada J, Márquez-Magaña L, and Samayoa C
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- Humans, Female, Male, Adult, Middle Aged, Community-Based Participatory Research, Hispanic or Latino psychology, Hispanic or Latino statistics & numerical data, Health Promotion methods, Research Personnel psychology, Patient Selection
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Latinx represent the second largest ethnic group in the USA and remain significantly underrepresented in research studies. Efforts to better include Latinx make use of community-engaged research (CEnR) approaches, peer-navigators, and cultural humility training for research teams. While these efforts have led to slight increases in Latinx participation, studies to identify strategic practices for better inclusion of Latinx participants are needed. The objective of this study was to qualitatively examine factors leading to successful recruitment and retention of Latinx participants in the Promoting Activity and Stress Reduction in the Outdoors (PASITO) intervention. For this intervention, 99 low-income Latinx clients in a local community were contacted and 52 participants were recruited (53%). All were retained in the 3-month intervention. Of these, 12 were interviewed within 6 months of the close of PASITO by bi-cultural and bi-lingual non-research staff. They conducted one-on-one structured telephone interviews. Of the twelve participants, three (25%) were men, nine (75%) were women, and the mean age was 43.7 (SD = 8.7). Four critical themes for the recruitment and retention of Latinx populations emerged from the interviews: (1) importance of insider researchers; (2) sense of community and belonging; (3) responsive programming; and (4) health-promoting activities. These findings support the significant role insider researchers can play, and social identity theory provides a useful framework for understanding the role of insider researchers in recruiting and retaining Latinx, and likely other minoritized groups, in clinical studies. Insider researchers possess the skills, training, community cultural wealth, in-depth understanding of their communities, and structural competencies that position them to carry out more inclusive studies to address the needs of marginalized communities and advance science., (© 2023. The Author(s).)
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- 2024
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10. Anti-deficit is anti-racist and transformative.
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Márquez-Magaña L
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For science to be socially transformative it must be anti-deficit, meaning it must oppose efforts aimed at correcting perceived deficiencies in individuals. Instead, asset-based approaches are needed that recognize and value cultural strengths instead of framing them as deficits to be masked. Such approaches foster inclusive and innovative research that better yields equitable solutions for populations burdened by structural racism., Competing Interests: The author declares no competing interests., (© 2024 The Author(s).)
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- 2024
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11. Virtual BUILD Research Collaboratory: A biomedical data science training using innovative pedagogy to address structures of racism and inequitable stress for undergraduates of color.
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Ceberio N, Le P, Bailey J, Vernard S, Coleman N, Carrasco YP, King T, Bibbins-Domingo K, Nguyen T, Parangan-Smith A, Uwaezuoke K, Rivers RC, Watson K, Márquez-Magaña L, and Mehta KM
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- Humans, Data Science, Workforce, Students, Racism prevention & control, Biomedical Research education
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Objective: The unprecedented events of 2020 required a pivot in scientific training to better prepare the biomedical research workforce to address global pandemics, structural racism, and social inequities that devastate human health individually and erode it collectively. Furthermore, this pivot had to be accomplished in the virtual environment given the nation-wide lockdown., Methods: These needs and context led to leveraging of the San Francisco Building Infrastructure Leading to Diversity (SF BUILD) theories of change to innovate a Virtual BUILD Research Collaboratory (VBRC). The purpose of VBRC was to train Black, Indigenous, and people of color (BIPOC) students to apply their unique perspectives to biomedical research. These training activities were evaluated using a pre-post survey design that included both validated and new psychosocial scales. A new scale was piloted to measure culturally relevant pedagogy., Results: VBRC scholars increased science identity on two items: thinking of myself as a scientist (+1point, p = 0.006) and belonging to a community of scientists (+1point, p = 0.069). Overall, scholars perceived stress also decreased over VBRC (-2.35 points, p = 0.02). Post VBRC, scholars had high agency scores (μ = 11.02, Md = 12, range = 6-12, σ = 1.62) and cultural humility scores (μ = 22.11, Md = 23, range = 12-24, σ = 2.71). No notable race/ethnic differences were found in any measures., Conclusions: Taken together, our innovative approach to data science training for BIPOC in unprecedented times shows promise for better preparing the workforce critically needed to address the fundamental gaps in knowledge at the intersection of public health, structural racism, and biomedical sciences., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Ceberio et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)
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- 2024
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12. Improving biology faculty diversity through a co-hiring policy and faculty agents of change.
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Harris M, Rosser S, Goldman M, Márquez-Magaña L, and Rohlfs RV
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- Humans, Ethnicity, Engineering, Biology, Faculty, Students
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Persons Excluded due to Ethnicity and Race (PEERs) remain underrepresented in university faculties, particularly in science, technology, engineering, math and medicine (STEMM) fields, despite increasing representation among students, and mounting evidence supporting the importance of PEER faculty in positively impacting both scientific and educational outcomes. In fact, the ratio of PEER faculty to students has been steadily dropping since 2000. In our case study, we examine the factors that explain creation of an unusually diverse faculty within a biology department. We analyzed nearly 40 years of hiring data in the study department and show that this department (the study department), historically and currently, maintains a significantly higher proportion of PEERs on faculty as compared to two national datasets. Additionally, we identify factors that contributed to hiring of PEERs into tenure and tenure-track positions. We observed a significant increase in the hiring of PEERs concurrent with the implementation of a co-hiring policy (p = 0.04) which allowed a single search to make two hires when at least one candidate was a PEER. In contrast, three key informants at sister departments reported that co-hiring policies did not result in PEER hires, but instead different practices were effective. In line with one of these practices, we observe a possible association between search committees with at least one PEER member and PEER hiring (p = 0.055). Further, the presence of particular faculty members (Agents of Change) on search committees is associated with PEER hiring. In this case study the combination of a co-hire policy based on the principle of interest-convergence to redress hiring inequities, along with the presence of agents of change, increased faculty PEER representation in STEMM departments., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Harris et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)
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- 2023
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13. Cortisol levels in rural Latina breast cancer survivors participating in a peer-delivered cognitive-behavioral stress management intervention: The Nuevo Amanecer-II RCT .
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Samayoa C, Santana-Ufret V, Santoyo-Olsson J, Strassle PD, Stewart A, Bonilla J, Escalera C, Mendez RM, Márquez-Magaña L, Ortiz C, Ceballos RM, and Nápoles AM
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Background: Compared to their White counterparts, Latina breast cancer survivors have poorer survival rates and health-related quality of life, and higher rates of depression and anxiety which may be a result of chronic stress. Chronic stress impacts the hypothalamic-pituitary-adrenal (HPA) axis, resulting in cortisol dysregulation which may be associated with breast cancer survival. However, cortisol levels and cortisol profiles of Latina breast cancer survivors are poorly characterized due to their underrepresentation in biomedical research., Objective: The objective of this study was to describe cortisol levels and patterns of cortisol secretions in rural Latina breast cancer survivors participating in an RCT study of Nuevo Amanecer-II , an evidence-based peer-delivered cognitive behavioral stress management intervention., Methods: Participant-centered recruitment and collection strategies were used to obtain biospecimens for cortisol analysis. Nine saliva samples (3/day for 3 days) and a hair sample were obtained at baseline and 6-months (3-months post-intervention). We describe cortisol levels and profiles, explore correlations of biomarkers with self-report measures of stress and psychological distress, and compare women who received the intervention with a delayed intervention group on biomarkers of stress. Mean hair cortisol concentration (HCC) was used to assess chronic stress. Based on daily measures of cortisol (awakening, 30 min post-awakening, and bedtime), we calculated three summary measures of the dynamic nature of the cortisol awakening response (CAR): 1) the CAR slope, 2) whether CAR demonstrates a percent change ≥40, and 3) total daily cortisol output (AUCg). Linear and log-binomial regression, accounting for multiple samples per participant, were used to compare cortisol measures at 6-month follow-up by treatment arm., Results: Participants (n = 103) were from two rural California communities; 76 provided at least one saliva sample at baseline and follow-up and were included in the analysis. At baseline, mean age was 57 years, mean years since diagnosis was 2 years, 76% had a high school education or less, and 34% reported financial hardship. The overall median CAR slope was 0.10, and median cortisol AUCg (in thousands) was 11.34 (range = 0.93, 36.66). Mean hair cortisol concentration was 1751.6 pg/mg (SD = 1148.6). Forty-two percent of samples had a ≥40% change in CAR. We found no statistically significant correlations between the cortisol measures and self-reported measures of stress and psychological distress. At follow-up, no differences were seen in HCC (mean difference between intervention and control: -0.11, 95% CI -0.48, 0.25), CAR slope (0.001, 95% CI -0.005, 0.008), cortisol AUCg (-0.15, 95% CI -0.42, 0.13), or ≥40% change in CAR (prevalence ratio 0.87, 95% CI 0.42, 1.77) between treatment arms., Conclusion: Our findings of flattened cortisol profiles among more than half of the sample suggest potential HPA-axis dysregulation among rural Spanish-speaking Latina breast cancer survivors that merits further study due to its implications for long-term survival., Trial Registration: http://www.ClinicalTrials.gov identifier NCT02931552., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors.)
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- 2022
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14. Superwoman Schema, Racial Identity, and Cellular Aging Among African American Women.
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Thomas MD, Mendez RM, Zhang Y, Wang Y, Sohail S, Chae DH, Márquez-Magaña L, Sellers R, Woods-Giscombé CL, and Allen AM
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- Adaptation, Psychological, Cellular Senescence, Female, Humans, Women's Health, Black or African American psychology, Racism psychology
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Background and Objectives: African American women experience faster telomere shortening (i.e., cellular aging) compared with other racial-gender groups. Prior research demonstrates that race and gender interact to influence culturally specific norms for responding to socially-relevant stress and other stress-coping processes, which may affect healthy aging., Research Design and Methods: Data are from African American Women's Heart & Health Study participants who consented to DNA extraction (n = 140). Superwoman Schema (SWS) was measured using 5 validated subscales: presenting strength, emotion suppression, resisting vulnerability, motivation to succeed, and obligation to help others. Racial identity was measured using 3 subscales from the Multidimensional Inventory of Black Identity: racial centrality, private regard, and public regard. Relative telomere length (rTL) was measured using DNA extracted from blood samples. Path analysis tested associations and interactions between SWS and racial identity dimensions with rTL., Results: For SWS, higher resistance to being vulnerable predicted longer telomeres. For racial identity, high private regard predicted longer telomeres while high public regard predicted shorter telomeres. Interactions were found between public regard and 2 SWS dimensions: among women with high public regard, emotion suppression (β = 0.20, p < .05) and motivation to succeed (β = 0.18, p < .05) were associated with longer rTL. The interaction between high centrality and emotion suppression predicted shorter rTL (β = -0.17, p < .05)., Discussion and Implications: Culturally specific responses to gendered racism and racial identity, developed early in life and shaped over the life course, are important psychosocial determinants of cellular aging among African American women., (© The Author(s) 2022. Published by Oxford University Press on behalf of The Gerontological Society of America.)
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- 2022
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15. Geospatial Distributions of Lead Levels Found in Human Hair and Preterm Birth in San Francisco Neighborhoods.
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Okorie CN, Thomas MD, Méndez RM, Di Giuseppe EC, Roberts NS, and Márquez-Magaña L
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- Black or African American, Humans, Infant, Newborn, Residence Characteristics, San Francisco epidemiology, Lead, Premature Birth epidemiology
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In San Francisco (SF), many environmental factors drive the unequal burden of preterm birth outcomes for communities of color. Here, we examine the association between human exposure to lead (Pb) and preterm birth (PTB) in 19 racially diverse SF zip codes. Pb concentrations were measured in 109 hair samples donated by 72 salons and barbershops in 2018-2019. Multi-method data collection included randomly selecting hair salons stratified by zip code, administering demographic surveys, and measuring Pb in hair samples as a biomarker of environmental exposure to heavy metals. Concentrations of Pb were measured by atomic emission spectrometry. Aggregate neighborhood Pb levels were linked to PTB and demographic data using STATA 16 SE (StataCorp LLC, College Station, TX, USA). Pb varied by zip code ( p < 0.001) and correlated with PTB ( p < 0.01). Increases in unadjusted Pb concentration predicted an increase in PTB (β = 0.003; p < 0.001) and after adjusting for poverty (β = 0.002; p < 0.001). Confidence intervals contained the null after further adjustment for African American/Black population density ( p = 0.16), suggesting that race is more indicative of high rates of PTB than poverty. In conclusion, Pb was found in every hair sample collected from SF neighborhoods. The highest concentrations were found in predominately African American/Black and high poverty neighborhoods, necessitating public health guidelines to eliminate this environmental injustice.
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- 2021
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16. Racial Discrimination and Telomere Length in Midlife African American Women: Interactions of Educational Attainment and Employment Status.
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Thomas MD, Sohail S, Mendez RM, Márquez-Magaña L, and Allen AM
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- Adult, Black or African American statistics & numerical data, Aging ethnology, Female, Humans, Middle Aged, Racism statistics & numerical data, San Francisco epidemiology, Women's Health ethnology, Black or African American ethnology, Cellular Senescence physiology, Educational Status, Employment, Racism ethnology, Social Class, Telomere Shortening physiology
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Background: Over the life course, African American (AA) women have faster telomere attrition, a biological indicator of accelerated aging, than White women. Race, sex, age, and composite socioeconomic status (SES) modify associations of institutional racial discrimination and telomere length. However, interactions with everyday racial discrimination have not been detected in AA women, nor have interactions with individual socioeconomic predictors., Purpose: We estimated statistical interaction of institutional and everyday racial discrimination with age, education, employment, poverty, and composite SES on telomere length among midlife AA women., Methods: Data are from a cross-section of 140 AA women aged 30-50 years residing in the San Francisco Bay Area. Participants completed questionnaires, computer-assisted self-interviews, physical examinations, and blood draws. Adjusted linear regression estimated bootstrapped racial discrimination-relative telomere length associations with interaction terms., Results: Racial discrimination did not interact with age, poverty, or composite SES measures to modify associations with telomere length. Interactions between independent SES variables were nonsignificant for everyday discrimination whereas institutional discrimination interacted with educational attainment and employment status to modify telomere length. After adjusting for covariates, we found that higher institutional discrimination was associated with shorter telomeres among employed women with lower education (β = -0.020; 95% confidence interval = -0.036, -0.003). Among unemployed women with higher education, higher institutional discrimination was associated with longer telomeres (β = 0.017; 95% confidence interval = 0.003, 0.032). Factors related to having a post-high school education may be protective against the negative effects of institutional racism on cellular aging for AA women., (© Society of Behavioral Medicine 2020. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
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- 2021
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17. Designing a biomedical coding program focused on inclusivity and agency.
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Mehta KM, Ceberio N, Vernard S, Carrasco YP, Bibbins-Domingo K, Nguyen TT, Lê P, Bailey J, Parangan-Smith A, Uwaezuoke K, Rivers RC, Watson K, and Márquez-Magaña L
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- 2021
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18. Baseline Characteristics of the 2015-2019 First Year Student Cohorts of the NIH Building Infrastructure Leading to Diversity (BUILD) Program.
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Norris KC, McCreath HE, Hueffer K, Aley SB, Chavira G, Christie CA, Crespi CM, Crespo C, D'Amour G, Eagan K, Echegoyen LE, Feig A, Foroozesh M, Guerrero LR, Johanson K, Kamangar F, Kingsford L, LaCourse W, Maccalla NM, Márquez-Magaña L, Mathur A, Maton K, Mehravaran S, Morales DX, Nakazono T, Ofili E, Okuyemi K, Ott L, Parangan-Smith A, Pfund C, Purnell D, Reynolds A, Rous PJ, Saetermoe C, Snyder K, Vishwanatha JK, Wagler A, Wallace SP, and Seeman T
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- Adolescent, Adult, Black or African American statistics & numerical data, Asian statistics & numerical data, Educational Status, Female, Hispanic or Latino statistics & numerical data, Humans, Income statistics & numerical data, Male, Middle Aged, National Institutes of Health (U.S.) economics, Native Hawaiian or Pacific Islander statistics & numerical data, Prospective Studies, Surveys and Questionnaires, United States, White People statistics & numerical data, Workforce, Young Adult, American Indian or Alaska Native statistics & numerical data, Biomedical Research education, Cultural Diversity, Government Programs statistics & numerical data, Students statistics & numerical data, Universities
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Objective: The biomedical/behavioral sciences lag in the recruitment and advancement of students from historically underrepresented backgrounds. In 2014 the NIH created the Diversity Program Consortium (DPC), a prospective, multi-site study comprising 10 Building Infrastructure Leading to Diversity (BUILD) institutional grantees, the National Research Mentoring Network (NRMN) and a Coordination and Evaluation Center (CEC). This article describes baseline characteristics of four incoming, first-year student cohorts at the primary BUILD institutions who completed the Higher Education Research Institute, The Freshmen Survey between 2015-2019. These freshmen are the primary student cohorts for longitudinal analyses comparing outcomes of BUILD program participants and non-participants., Design: Baseline description of first-year students entering college at BUILD institutions during 2015-2019., Setting: Ten colleges/universities that each received <$7.5mil/yr in NIH Research Project Grants and have high proportions of low-income students., Participants: First-year undergraduate students who participated in BUILD-sponsored activities and a sample of non-BUILD students at the same BUILD institutions. A total of 32,963 first-year students were enrolled in the project; 64% were female, 18% Hispanic/Latinx, 19% African American/Black, 2% American Indian/Alaska Native and Native Hawaiian/Pacific Islander, 17% Asian, and 29% White. Twenty-seven percent were from families with an income <$30,000/yr and 25% were their family's first generation in college., Planned Outcomes: Primary student outcomes to be evaluated over time include undergraduate biomedical degree completion, entry into/completion of a graduate biomedical degree program, and evidence of excelling in biomedical research and scholarship., Conclusions: The DPC national evaluation has identified a large, longitudinal cohort of students with many from groups historically underrepresented in the biomedical sciences that will inform institutional/national policy level initiatives to help diversify the biomedical workforce., Competing Interests: Competing Interests: None declared., (Copyright © 2020, Ethnicity & Disease, Inc.)
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- 2020
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19. Systemic racism in higher education.
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Barber PH, Hayes TB, Johnson TL, and Márquez-Magaña L
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- Engineering, Humans, Mathematics, Science, Technology, United States, Academies and Institutes, Racism, Universities
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- 2020
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20. Participant-Centered Strategies for Overcoming Barriers to Biospecimen Collection among Spanish-Speaking Latina Breast Cancer Survivors.
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Samayoa C, Santoyo-Olsson J, Escalera C, Stewart AL, Ortiz C, Márquez-Magaña L, Urias A, Gonzalez N, Cervantes SA, Torres-Nguyen A, Parada-Ampudia L, and Nápoles AM
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- Adult, Aged, Aged, 80 and over, Breast Neoplasms genetics, California, Cancer Survivors statistics & numerical data, Community-Based Participatory Research, Culturally Competent Care methods, Culturally Competent Care organization & administration, Culturally Competent Care statistics & numerical data, DNA genetics, DNA isolation & purification, Feasibility Studies, Female, Follow-Up Studies, Hair chemistry, Hispanic or Latino psychology, Hispanic or Latino statistics & numerical data, Humans, Middle Aged, Minority Groups psychology, Minority Groups statistics & numerical data, Patient Participation statistics & numerical data, Patient-Centered Care methods, Program Evaluation, Saliva chemistry, Specimen Handling psychology, Specimen Handling statistics & numerical data, Biomarkers, Tumor genetics, Breast Neoplasms diagnosis, Cancer Survivors psychology, Patient Participation psychology
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Background: Latinos are underrepresented in biomedical research, particularly biomarker research, yet they constitute the nation's largest ethnic/racial minority. Optimal methods for obtaining biospecimens for biomarker research among Latinos need to be identified. To minimize barriers and enhance participation, this study developed and tested tailored strategies for collecting biomarkers of chronic stress and premature aging among Spanish-speaking Latina breast cancer survivors., Methods: This study used a community-based participatory approach and selected hair and saliva as noninvasive biospecimens to assess telomere length, the cortisol awakening response (CAR), and hair cortisol concentration. We developed bilingual multimedia instructional materials, and community health workers assisted in collections. Telephone surveys assessed willingness to participate in future studies, barriers to sample collection, and recommendations for improving the strategies., Results: A total of 103 participants were recruited over 18 months from two rural sites in California, and 88 were retained at 6-month follow-up. At baseline, rates of donating salivary DNA for telomere length measurement, saliva for CAR analysis, and hair for cortisol concentration were 98%, 89%, and 52%, respectively. At follow-up, rates were 83%, 76%, and 55%, respectively. The majority of participants reported being very willing to provide hair (72%) or saliva (74%) for future studies., Conclusions: Our results support the feasibility of including minorities in biomedical research. We report excellent rates of saliva collection when community partners are engaged in the process, and when patient-centered and culturally tailored recruitment methods are implemented., Impact: The development of methods to facilitate the inclusion of minorities in biomedical research is critical to eliminate racial/ethnic health disparities., (©2020 American Association for Cancer Research.)
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- 2020
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21. The Influence of Microaffirmations on Undergraduate Persistence in Science Career Pathways.
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Estrada M, Young GR, Nagy J, Goldstein EJ, Ben-Zeev A, Márquez-Magaña L, and Eroy-Reveles A
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- Factor Analysis, Statistical, Female, Humans, Male, Minority Groups, Models, Educational, Self Efficacy, Young Adult, Career Choice, Science education, Students
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The present studies aimed to advance the measurement and understanding of microaffirmation kindness cues and assessed how they related to historically underrepresented (HU) and historically overrepresented (HO) undergraduate student persistence in science-related career pathways. Study 1 developed and tested the dimensionality of a new Microaffirmations Scale. Study 2 confirmed the two-factor structure of the Microaffirmations Scale and demonstrated that the scale possessed measurement invariance across HU and HO students. Further, the scale was administered as part of a longitudinal design spanning 9 months, with results showing that students' reported microaffirmations did not directly predict higher intentions to persist in science-related career pathways 9 months later. However, scientific self-efficacy and identity, measures of student integration into the science community, mediated this relationship. Overall, our results demonstrated that microaffirmations can be measured in an academic context and that these experiences have predictive value when they increase students' integration into their science communities, ultimately resulting in greater intentions to persist 9 months later. Researchers and practitioners can use the Microaffirmations Scale for future investigations to increase understanding of the positive contextual factors that can ultimately help reduce persistence gaps in science, technology, engineering, and mathematics degree attainment.
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- 2019
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22. Gut Microbiota Composition Is Related to Cardiorespiratory Fitness in Healthy Young Adults.
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Durk RP, Castillo E, Márquez-Magaña L, Grosicki GJ, Bolter ND, Lee CM, and Bagley JR
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- Adult, Bacteroidetes isolation & purification, Diet, Exercise, Female, Firmicutes isolation & purification, Gastrointestinal Tract microbiology, Humans, Male, Oxygen Consumption, Young Adult, Cardiorespiratory Fitness, Gastrointestinal Microbiome
- Abstract
Bacteria residing in the human gastrointestinal tract has a symbiotic relationship with its host. Animal models have demonstrated a relationship between exercise and gut microbiota composition. This was the first study to explore the relationship between cardiorespiratory fitness (maximal oxygen consumption, VO
2 max) and relative gut microbiota composition (Firmicutes to Bacteroidetes ratio [F/B]) in healthy young adults in a free-living environment. Twenty males and 17 females (25.7 ± 2.2 years), who did not take antibiotics in the last 6 months, volunteered for this study. VO2 max was measured using a symptom-limited graded treadmill test. Relative microbiota composition was determined by analyzing DNA extracted from stool samples using a quantitative polymerase chain reaction that specifically measured the quantity of a target gene (16S rRNA) found in Firmicutes and Bacteroidetes. Relationships between F/B and potentially related dietary, anthropometric, and fitness variables were assessed using correlation analyses with an appropriate Bonferroni adjustment ( p < .004). The average F/B ratio in all participants was 0.94 ± 0.03. The F/B ratio was significantly correlated to VO2 max ( r = .48, p < .003), but no other fitness, nutritional intake, or anthropometric variables ( p > .004). VO2 max explained ∼22% of the variance of an individual's relative gut bacteria as determined by the F/B ratio. These data support animal findings, demonstrating a relationship between relative human gut microbiota composition and cardiorespiratory fitness in healthy young adults. Gastrointestinal bacteria is integral in regulating a myriad of physiological processes, and greater insight regarding ramifications of exercise and nutrition on gut microbial composition may help guide therapies to promote human health.- Published
- 2019
- Full Text
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23. Healthy Parks Healthy People as an Upstream Stress Reduction Strategy.
- Author
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Yoshino A, Wilson J, Velazquez EJ, Johnson E, and Márquez-Magaña L
- Abstract
One of the primary goals of the Healthy Parks Healthy People (HPHP) program, located in the San Francisco Bay Area, is to offer group-based physical activities in natural settings. These activities arefor racially and ethnically diverse groups of individuals as an "upstream" strategy for improving health. This study investigated the health impact of selected two-hour HPHP Bay Area events that targeted low-income racial and ethnic minority groups using physiological and self-reported measures of stress and related variables. Study participants (N=52) in the selected HPHP Bay Area events donated saliva and filled out psychological measures of perceived stress (PSS-4; Cohen et al.) and mood state (I-PANAS-SF; Thompson, 2007) at the beginning and the end ofa two-hour guided walk in green spaces. Moreover, a measure of perceived restoration (SRRS; Han, 2007) was completed at the end ofthe walk. Study participants wore a physical activity self-monitoring device (Garmin Vivofit 2) to capture their step count and heart rate during the event. Stress, both measured by the analysis of salivary cortisol and self-reported perceived stress, significantly decreased over the course of the event (p<.0$) and there was a significant increase in positive mood (p<.05). The monitoring device also indicated that individuals were engaged in moderate levels of physical activity during the guided walks (
x =8,990 steps, HR 95 bpm). The results encourage further development of nature-based health interventions to mitigate stress. Such interventions may be especially appropriate for low-income, urban, racial and ethnic minority groups that likely experience increased levels of stress due to social inequities and poor living conditions.- Published
- 2018
- Full Text
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24. Enabling full representation in science: the San Francisco BUILD project's agents of change affirm science skills, belonging and community.
- Author
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Estrada M, Eroy-Reveles A, Ben-Zeev A, Baird T Jr, Domingo C, Gómez CA, Bibbins-Domingo K, Parangan-Smith A, and Márquez-Magaña L
- Abstract
Background: The underrepresentation of minority students in the sciences constrains innovation and productivity in the U.S. The SF BUILD project mission is to remove barriers to diversity by taking a "fix the institution" approach rather than a "fix the student" one. SF BUILD is transforming education, research, training, and mentoring at San Francisco State University, a premiere public university that primarily serves undergraduates and ethnic minority students. It boasts a large number of faculty members from underrepresented groups (URGs), including many of the project leaders. These leaders collaborate with faculty at the University of California San Francisco (UCSF), a world-class medical research institution, to implement SF BUILD., Key Highlights: Together, the campus partners are committed to creating intellectually safe and affirming environments grounded in the Signaling Affirmation for Equity (SAFE) model, which is based on robust psychosocial evidence on stereotype threat and its consequences. The SAFE model dictates a multilevel approach to increasing intent to pursue a biomedical career, persistence in STEM fields, and productivity (e.g. publications, presentations, and grants) by implementing transformative activities at the institutional, faculty, and student levels. These activities (1) increase knowledge of the stereotype threat phenomenon; (2) affirm communal and altruistic goals of students and faculty to "give back" to their communities in classrooms and research activities; and (3) establish communities of students, faculty and administrators as "agents of change." Agents of change are persons committed to establishing and maintaining SAFE environments. In this way, SF BUILD advances the national capacity to address biomedical questions relevant to communities of color by enabling full representation in science., Implications: This chapter describes the theoretical and historical context that drive the activities, research and evaluation of the SF BUILD project, and highlights attributes that other institutions can use for institutional change. While this paper is grounded in psychosocial theory, it also provides practical solutions for broadening participation., Competing Interests: Not ApplicableNot ApplicableThe authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
- Published
- 2017
- Full Text
- View/download PDF
25. Enhancing Biospecimen Knowledge Among Health Care Providers and Representatives From Community Organizations.
- Author
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Tham HM, Hohl S, Copeland W, Briant KJ, Márquez-Magaña L, and Thompson B
- Subjects
- Adolescent, Adult, Female, Humans, Male, Middle Aged, Young Adult, Ethnicity education, Health Education organization & administration, Health Knowledge, Attitudes, Practice, Neoplasms ethnology, Neoplasms pathology, Specimen Handling psychology
- Abstract
In a personalized medicine environment, it is necessary to have access to a range of biospecimens to establish optimal plans for disease diagnosis and treatment for individual patients. Cancer research is especially dependent on biospecimens for determining ideal personalized treatment for patients. Unfortunately, the vast majority of biospecimens are collected from non-Hispanic White individuals; thus, minority representation is lacking. This has negative implications for comprehensive cancer treatment. The Geographic Management of Cancer Health Disparities Program (GMaP) Region 6 implemented a series of biospecimen education seminars adapted from the Biospecimen and Biobanking module of an existing Cancer Education and Training Program. Regional GMaP partners participated in a train-the-trainer webinar to familiarize themselves with the training materials. Participants trained by the trainers completed pre- and posttests to document changes in awareness, knowledge, and intention. Nine biospecimen education seminars were offered in 2013; 255 health care professionals and representatives from community organizations attended. Participants demonstrated a significant increase in knowledge, intention to donate samples, and intention to talk to patients about biospecimen sample donation. Representatives from community organizations had more improvement on knowledge scores than health care providers. Participation in a well-designed biospecimen education program may ameliorate some of the distrust of biomedical research experienced by racial/ethnic minorities and, in turn, increase needed minority representation in biospecimen collection.
- Published
- 2017
- Full Text
- View/download PDF
26. 'Speaking Truth' Protects Underrepresented Minorities' Intellectual Performance and Safety in STEM.
- Author
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Ben-Zeev A, Paluy Y, Milless KL, Goldstein EJ, Wallace L, Márquez-Magaña L, Bibbins-Domingo K, and Estrada M
- Abstract
We offer and test a brief psychosocial intervention, Speaking Truth to EmPower (STEP), designed to protect underrepresented minorities' (URMs) intellectual performance and safety in science, technology, engineering, and math (STEM). STEP takes a 'knowledge as power' approach by: (a) providing a tutorial on stereotype threat (i.e., a social contextual phenomenon, implicated in underperformance and early exit) and (b) encouraging URMs to use lived experiences for generating be-prepared coping strategies. Participants were 670 STEM undergraduates [URMs (Black/African American and Latina/o) and non-URMs (White/European American and Asian/Asian American)]. STEP protected URMs' abstract reasoning and class grades (adjusted for grade point average [GPA]) as well as decreased URMs' worries about confirming ethnic/racial stereotypes. STEP's two-pronged approach-explicating the effects of structural 'isms' while harnessing URMs' existing assets-shows promise in increasing diversification and equity in STEM., Competing Interests: Conflicts of Interest: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.
- Published
- 2017
- Full Text
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27. Evaluation of cortisol and telomere length measurements in ethnically diverse women with breast cancer using culturally sensitive methods.
- Author
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Ramirez J, Elmofty M, Castillo E, DeRouen M, Shariff-Marco S, Allen L, Gomez SL, Nápoles AM, and Márquez-Magaña L
- Abstract
The under-representation of ethnic minority participants, who are more likely to be socially disadvantaged in biomedical research, limits generalizability of results and reductions in health disparities. To facilitate investigations of how social disadvantage "gets under the skin," this pilot study evaluated low-intensity methods for collecting hair and saliva samples from multiethnic breast cancer survivors (N = 70) and analysis of biomarkers of chronic stress (cortisol levels) and biological age (telomere length). Methods allowed for easy self-collection of hair (for cortisol) and saliva (for telomere lengths) samples that were highly stable for shipment and long-term storage. Measuring cortisol in hair as a biomarker of chronic stress was found to overcome many of the limitations of salivary cortisol measurements, and the coefficient of variation obtained using an ELISA-based approach to measure cortisol was within acceptable standards (16%). Telomere length measurements obtained using a qPCR approach had a coefficient of variation of <10% when the DNA extracted from the saliva biospecimens was of sufficient quantity and quality (84%). The overall response rate was 47%; rates were 32% for African-Americans, 39% for Latinas, 40% for Asians, and 82% for non-Latina Whites. Self-collection of hair and saliva overcame cultural and logistical barriers associated with collection of blood. Results support the use of these biospecimen collection and analysis methods among ethnically diverse and disadvantaged populations to identify biopsychosocial pathways of health disparities. Our tools should stimulate research to better understand how social disadvantage "gets under the skin" and increase participation of ethnic minorities in biomedical research.
- Published
- 2017
- Full Text
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28. Near-peer STEM Mentoring Offers Unexpected Benefits for Mentors from Traditionally Underrepresented Backgrounds.
- Author
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Trujillo G, Aguinaldo PG, Anderson C, Bustamante J, Gelsinger DR, Pastor MJ, Wright J, Márquez-Magaña L, and Riggs B
- Published
- 2015
29. Debunking 'race' and asserting social determinants as primary causes of cancer health disparities: outcomes of a science education activity for teens.
- Author
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Márquez-Magaña L, Samayoa C, and Umanzor C
- Subjects
- Adolescent, Cause of Death, DNA, Mitochondrial genetics, Female, Gene-Environment Interaction, Genetic Loci, Genetic Predisposition to Disease genetics, Genetic Variation genetics, Humans, Male, Neoplasms mortality, Risk Factors, SEER Program, Sequence Analysis, DNA, Survival Rate, United States, Ethnicity genetics, Health Status Disparities, Neoplasms ethnology, Neoplasms genetics, Science education, Socioeconomic Factors
- Abstract
Cancer health disparities are often described as the unequal burden of cancer deaths in one racial/ethnic group compared to another. For example, national cancer statistics in the USA shows that Blacks die the most for 9 of the top 10 cancers in men and women. When asked about the underlying causes for this disparity, teen participants speculated that it is primarily due to genetics or biology. This speculation appears to be based on a false concept of 'race.' A science activity was created to counter the false concept that genetics/biology underlie the categorization of humans into different 'races.' This activity provided teen participants with first-hand evidence of how they are all related at one genetic locus, and how they are more genetically related across racial/ethnic groups than within them. Results of surveys given before and after the activity show that they change their perceptions of 'race.' Before the activity, they view themselves as most related at the genetic level to 1-2 well-known individuals (i.e., celebrities) who they perceive as members of their own 'race' mainly because of similar appearance. After the activity, they view themselves as related to more/all the celebrities or they state that they do not know to whom they are most related. This increased awareness of the uncertainty between the apparent 'race' of an individual and their genetics drives teens to dismiss genetics or biology as the primary cause of racial/ethnic disparities in cancer outcomes. Instead, they consider the unequal distribution of the social determinants of health as the primary cause of cancer disparities.
- Published
- 2013
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30. Factors influencing time to diagnosis after abnormal mammography in diverse women.
- Author
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Pérez-Stable EJ, Afable-Munsuz A, Kaplan CP, Pace L, Samayoa C, Somkin C, Nickleach D, Lee M, Márquez-Magaña L, Juarbe T, and Pasick RJ
- Subjects
- Adult, Aged, Aged, 80 and over, Biopsy, Breast Neoplasms diagnostic imaging, Breast Neoplasms ethnology, Confidence Intervals, Female, Follow-Up Studies, Health Knowledge, Attitudes, Practice, Health Services Accessibility, Health Surveys, Humans, Incidence, Middle Aged, San Francisco epidemiology, Socioeconomic Factors, Telephone, Time Factors, Breast Neoplasms diagnosis, Ethnicity statistics & numerical data, Mammography statistics & numerical data, Mass Screening statistics & numerical data
- Abstract
Background: Abnormal mammograms are common, and the risk of false positives is high. We surveyed women in order to understand the factors influencing the efficiency of the evaluation of an abnormal mammogram., Methods: Women aged 40-80 years, identified from lists with Breast Imaging Reporting and Data System (BIRADS) classifications of 0, 3, 4, or 5, were surveyed. Telephone surveys asked about the process of evaluation, and medical records were reviewed for tests and timing of evaluation., Results: In this study, 970 women were surveyed, and 951 had chart reviews. Overall, 36% were college graduates, 68% were members of a group model health plan, 18% were Latinas, 25% were African Americans, 15% were Asian, and 43% were white. Of the 352 women who underwent biopsies, 151 were diagnosed with cancer (93 invasive). Median time to diagnosis was 183 days for BIRADS 3 compared to 29 days for BIRADS 4/5 and 27 days for BIRADS 0. At 60 days, 84% of BIRADS 4/5 women had a diagnosis. Being African American (hazard ratio [HR] 0.69, 95% confidence interval [CI] 0.49-0.97, p=0.03), income < $10,000 (HR 0.55, 95% CI 0.31-0.98, p<0.04), perceived discrimination (HR 0.22, 95% CI 0.09-0.52, p<0.001), not fully understanding the results of the index mammogram (HR 0.49, 95% CI 0.32-0.75, p=0.001), and being notified by letter (HR 0.66, 95% CI 0.48-0.90, p=0.01) or telephone (HR 0.62, 95% CI 0.42-0.92, p=0.02) rather than in person were all associated with significant delays in diagnosis., Conclusions: Evaluation of BIRADS 0, 4, or 5 abnormal mammograms was completed in most women within the recommended 60 days. Even within effective systems, correctible communication factors may adversely affect time to diagnosis.
- Published
- 2013
- Full Text
- View/download PDF
31. The extracytoplasmic function sigma factor SigY is important for efficient maintenance of the Spβ prophage that encodes sublancin in Bacillus subtilis.
- Author
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Mendez R, Gutierrez A, Reyes J, and Márquez-Magaña L
- Subjects
- Anti-Bacterial Agents pharmacology, Bacillus subtilis cytology, Bacillus subtilis drug effects, Drug Resistance, Bacterial genetics, Sigma Factor deficiency, Spores, Bacterial physiology, Anti-Bacterial Agents metabolism, Bacillus subtilis genetics, Bacillus subtilis virology, Bacterial Proteins metabolism, Cytoplasm metabolism, Prophages genetics, Sigma Factor metabolism
- Abstract
Many strains of the soil bacterium Bacillus subtilis are capable of producing and being resistant to the antibiotic sublancin because they harbor the Spβ prophage. This 135 kb viral genome is integrated into the circular DNA chromosome of B. subtilis, and contains genes for the production of and resistance to sublancin. We investigated the role of SigY in sublancin production and resistance, finding that it is important for efficient maintenance of the Spβ prophage. We were unable to detect the prophage in mutants lacking SigY. Additionally, these mutants were no longer able to produce sublancin, were sensitive to killing by this factor, and displayed a delay in sporulation. Wild-type cells with normal SigY activity were found to partially lose the Spβ prophage during growth and early sporulation, suggesting a mechanism for the bistable outcome of sibling cells capable of killing and of being killed. The appropriate regulation of SigY appears to be essential for growth as evidenced by the inability to disrupt the gene for its putative antisigma. Our results confirm a role for SigY in antibiotic production and resistance, as has been found for other members of the extracytoplasmic function sigma factor family in B. subtilis, and shows that this role is achieved by affecting maintenance of the Spβ prophage.
- Published
- 2012
- Full Text
- View/download PDF
32. Investigative cases and student outcomes in an upper-division cell and molecular biology laboratory course at a minority-serving institution.
- Author
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Knight JD, Fulop RM, Márquez-Magaña L, and Tanner KD
- Subjects
- Animals, Attitude, Chickens, Goals, Humans, Interviews as Topic, Learning, Videotape Recording, Curriculum, Laboratories, Minority Groups education, Molecular Biology education, Program Evaluation, Students, Universities
- Abstract
Active-learning strategies are increasingly being integrated into college-level science courses to make material more accessible to all students and to improve learning outcomes. One active-learning pedagogy, case-based learning (CBL), was developed as a way to both enhance engagement in the material and to accommodate diverse learning styles. Yet, adoption of CBL approaches in undergraduate biology courses has been piecemeal, in part because of the perceived investment of time required. Furthermore, few CBL lesson plans have been developed specifically for upper-division laboratory courses. Here, we describe four cases that we developed and implemented for a senior cell and molecular biology laboratory course at San Francisco State University, a minority-serving institution. To evaluate the effectiveness of these modules, we used both written and verbal assessments to gauge learning outcomes and attitudinal responses of students over two semesters. Students responded positively to the new approach and seemed to meet the learning goals for the course. Most said they would take a course using CBL again. These case modules are readily adaptable to a variety of classroom settings.
- Published
- 2008
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- View/download PDF
33. The last gene of the fla/che operon in Bacillus subtilis, ylxL, is required for maximal sigmaD function.
- Author
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Werhane H, Lopez P, Mendel M, Zimmer M, Ordal GW, and Márquez-Magaña LM
- Subjects
- Bacterial Proteins metabolism, Chemotaxis, DNA-Directed RNA Polymerases, Flagella metabolism, Flagellin genetics, Flagellin metabolism, Movement, Bacillus subtilis physiology, Bacterial Proteins genetics, Gene Expression Regulation, Bacterial, Operon, Sigma Factor metabolism
- Abstract
ylxL was found to be the last gene of the fla/che operon in Bacillus subtilis and is cotranscribed with the gene for the flagellum-specific alternate sigma factor, sigma(D). The ylxL gene was disrupted by insertional mutagenesis, and the resultant mutant strain was found to be compromised for sigma(D)-dependent functions.
- Published
- 2004
- Full Text
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34. Regulation of the Bacillus subtilis extracytoplasmic function protein sigma(Y) and its target promoters.
- Author
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Cao M, Salzberg L, Tsai CS, Mascher T, Bonilla C, Wang T, Ye RW, Márquez-Magaña L, and Helmann JD
- Subjects
- Bacillus subtilis genetics, Bacterial Proteins genetics, Base Sequence, Cytoplasm, DNA Transposable Elements, Molecular Sequence Data, Mutagenesis, Insertional, Mutation, Oligonucleotide Array Sequence Analysis, Operon, Proteome, Sigma Factor genetics, Transcription, Genetic, Bacillus subtilis metabolism, Bacterial Proteins metabolism, Gene Expression Regulation, Bacterial, Promoter Regions, Genetic genetics, Sigma Factor metabolism
- Abstract
The Bacillus subtilis extracytoplasmic function sigma factor sigma(Y) is of unknown function. We demonstrate that the sigY operon is expressed from an autoregulatory promoter site, P(Y). We selected for transposon-induced mutations that upregulate P(Y) transcription in an attempt to identify genes involved in sigma(Y) regulation. The resulting insertions disrupted yxlC, the gene immediately downstream of sigY. However, the phenotype of the yxlC::Tn10 insertion was due to polarity on the downstream genes of the sigY operon; a nonpolar insertion in yxlC did not lead to derepression of P(Y). Further analyses revealed that both yxlD and yxlE encoded proteins important for the negative regulation of sigma(Y) activity. A comparison of the transcriptomes of wild-type and yxlC::Tn10 mutant strains revealed elevated expression of several operons. However, only one additional gene, ybgB, was unambiguously identified as a direct target for sigma(Y). This was supported by analysis of direct targets for sigma(Y) transcription with whole-genome runoff transcription followed by macroarray analysis.
- Published
- 2003
- Full Text
- View/download PDF
35. Relative roles of the fla/che P(A), P(D-3), and P(sigD) promoters in regulating motility and sigD expression in Bacillus subtilis.
- Author
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West JT, Estacio W, and Márquez-Magaña L
- Subjects
- Bacillus subtilis physiology, Base Sequence, DNA, Bacterial, Molecular Sequence Data, Bacillus subtilis genetics, Bacterial Proteins genetics, DNA-Directed RNA Polymerases genetics, Flagellin, Gene Expression Regulation, Bacterial, Genes, Bacterial, Operon, Promoter Regions, Genetic, Sigma Factor genetics
- Abstract
Three promoters have been identified as having potentially important regulatory roles in governing expression of the fla/che operon and of sigD, a gene that lies near the 3' end of the operon. Two of these promoters, fla/che P(A) and P(D-3), lie upstream of the >26-kb fla/che operon. The third promoter, P(sigD), lies within the operon, immediately upstream of sigD. fla/che P(A), transcribed by E sigma(A), lies >/=24 kb upstream of sigD and appears to be largely responsible for sigD expression. P(D-3), transcribed by E sigma(D), has been proposed to participate in an autoregulatory positive feedback loop. P(sigD), a minor sigma(A)-dependent promoter, has been implicated as essential for normal expression of the fla/che operon. We tested the proposed functions of these promoters in experiments that utilized strains that bear chromosomal deletions of fla/che P(A), P(D-3), or P(sigD). Our analysis of these strains indicates that fla/che P(A) is absolutely essential for motility, that P(D-3) does not function in positive feedback regulation of sigD expression, and that P(sigD) is not essential for normal fla/che expression. Further, our results suggest that an additional promoter(s) contributes to sigD expression.
- Published
- 2000
- Full Text
- View/download PDF
36. Environmental regulation of Bacillus subtilis sigma(D)-dependent gene expression.
- Author
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Mirel DB, Estacio WF, Mathieu M, Olmsted E, Ramirez J, and Márquez-Magaña LM
- Subjects
- Amino Acids, Culture Media, Flagellin biosynthesis, Genes, Reporter, RNA, Bacterial biosynthesis, RNA, Messenger biosynthesis, Bacillus subtilis physiology, Bacterial Proteins genetics, DNA-Binding Proteins, DNA-Directed RNA Polymerases metabolism, Gene Expression Regulation, Bacterial, Repressor Proteins genetics, Sigma Factor metabolism
- Abstract
The sigma(D) regulon of Bacillus subtilis is composed of genes encoding proteins for flagellar synthesis, motility, and chemotaxis. Concurrent analyses of sigma(D) protein levels and flagellin mRNA demonstrate that sigD expression and sigma(D) activity are tightly coupled during growth in both complex and minimal media, although they exhibit different patterns of expression. We therefore used the sigma(D)-dependent flagellin gene (hag) as a model gene to study the effects of different nutritional environments on sigma(D)-dependent gene expression. In complex medium, the level of expression of a hag-lacZ fusion increased exponentially during the exponential growth phase and peaked early in the transition state. In contrast, the level of expression of this reporter remained constant and high throughout growth in minimal medium. These results suggest the existence of a nutritional signal(s) that affects sigD expression and/or sigma(D) activity. This signal(s) allows for nutritional repression early in growth and, based on reconstitution studies, resides in the complex components of sporulation medium, as well as in a mixture of mono-amino acids. However, the addition of Casamino Acids to minimal medium results in a dose-dependent decrease in hag-lacZ expression throughout growth and the postexponential growth phase. In work by others, CodY has been implicated in the nutritional repression of several genes. Analysis of a codY mutant bearing a hag-lacZ reporter revealed that flagellin expression is released from nutritional repression in this strain, whereas mutations in the transition state preventor genes abrB, hpr, and sinR failed to elicit a similar effect during growth in complex medium. Therefore, the CodY protein appears to be the physiologically relevant regulator of hag nutritional repression in B. subtilis.
- Published
- 2000
- Full Text
- View/download PDF
37. Analysis of flagellin gene expression in flagellar phase variants of Campylobacter jejuni 81116.
- Author
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Nuijten PJ, Márquez-Magaña L, and van der Zeijst BA
- Subjects
- Bacterial Proteins genetics, Base Sequence, Campylobacter jejuni genetics, Flagella genetics, Flagellin biosynthesis, Genes, Bacterial genetics, Molecular Sequence Data, Promoter Regions, Genetic genetics, Sequence Analysis, DNA, Sequence Homology, Nucleic Acid, Sigma Factor genetics, Transcription, Genetic, Campylobacter jejuni physiology, Flagellin genetics, Gene Expression Regulation, Bacterial physiology
- Abstract
Flagella production in Campylobacter jejuni 81116 is subject to phase variation; the bacterium is able to switch its flagellum synthesis, and thereby its motility, on and off. Under standard laboratory growth conditions flagellar phase variants can be maintained as stable, pure cultures. We found conditions that efficiently induced a phase shift in vitro. The flaA gene but not the flaB gene is subject to the on and off switch. Minor amounts of FlaB are still present in aflagellate cells. We previously showed that flagellin gene expression in phase variants was regulated at the transcriptional level. Here, sequence data prove that abolishment of flaA transcription is not caused by DNA rearrangements or mutations within the flagellin locus. Since flaA is preceded by a typical sigma 28 promoter a C. jejuni sigma 28 homolog could play a role in regulation of flaA gene expression but such a gene or protein could not be detected. However, in vitro transcription could be detected using sigma 28-holoenzyme preparations from Bacillus subtilis. Possible regulatory mechanisms that may control flagellar phase variation in Campylobacter are discussed.
- Published
- 1995
- Full Text
- View/download PDF
38. Sequence and characterization of Bacillus subtilis CheW.
- Author
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Hanlon DW, Márquez-Magaña LM, Carpenter PB, Chamberlin MJ, and Ordal GW
- Subjects
- Amino Acid Sequence, Aspartic Acid metabolism, Base Sequence, Blotting, Southern, Chloramphenicol O-Acetyltransferase genetics, DNA, Bacterial genetics, Deoxyglucose metabolism, Electrophoresis, Polyacrylamide Gel, Genes, Bacterial, Genetic Complementation Test, Molecular Sequence Data, Open Reading Frames, Plasmids, Restriction Mapping, Sequence Alignment, Bacillus subtilis genetics, Bacterial Proteins genetics, Chemotactic Factors genetics, Escherichia coli Proteins
- Abstract
A Bacillus subtilis open reading frame (ORF) encoding a predicted polypeptide of 156 amino acids was subcloned and sequenced. The polypeptide was found to be homologous to CheW of Escherichia coli, sharing 28.6% amino acid identity. The ORF was verified by using a bacteriophage T7 expression system in E. coli. The gene was inactivated by insertion of a nonpolor chloramphenicol acetyltransferase cassette in its N-terminal region. In the absence of chemoeffectors, the mutant displayed a smooth swimming bias, with some tumbling. The CheW- mutant was defective on swarm plates but was complemented by a plasmid that expressed wild type CheW. Addition of attractant or repellent to the CheW- mutant resulted in transient smooth swimming or tumbling, respectively. However, capillary assays revealed that chemotaxis was substantially impaired in the mutant strain.
- Published
- 1992
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