Publications by authors named "C Alberto Figueroa"

551 Publications

Nucleotide-sugar metabolism in plants: the legacy of Luis F. Leloir.

J Exp Bot 2021 May 5. Epub 2021 May 5.

Instituto de Agrobiotecnología del Litoral, UNL, CONICET, FBCB, Colectora Ruta Nacional 168 km 0, 3000 Santa Fe,Argentina.

This review commemorates the 50th anniversary of the Nobel Prize in Chemistry awarded to Luis F. Leloir 'for his discovery of sugar-nucleotides and their role in the biosynthesis of carbohydrates'. He and his co-workers discovered that activated forms of simple sugars, such as UDP-glucose and UDP-galactose, are essential intermediates in the interconversion of sugars. They elucidated the biosynthetic pathways for sucrose and starch, which are the major end-products of photosynthesis, and for trehalose. Trehalose 6-phosphate, the intermediate of trehalose biosynthesis that they discovered, is now a molecule of great interest due to its function as a sugar signalling metabolite that regulates many aspects of plant metabolism and development. The work of the Leloir group also opened the doors to an understanding of the biosynthesis of cellulose and other structural cell wall polysaccharides (hemicelluloses and pectins), and ascorbic acid (vitamin C). Nucleotide-sugars also serve as sugar donors for a myriad of glycosyltransferases that conjugate sugars to other molecules, including lipids, phytohormones, secondary metabolites, and proteins, thereby modifying their biological activity. In this review, we highlight the diversity of nucleotide-sugars and their functions in plants, in recognition of Leloir's rich and enduring legacy to plant science.
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http://dx.doi.org/10.1093/jxb/erab109DOI Listing
May 2021

Ethylene application at the immature stage of Fragaria chiloensis fruit represses the anthocyanin biosynthesis with a concomitant accumulation of lignin.

Food Chem 2021 Apr 20;358:129913. Epub 2021 Apr 20.

Institute of Biological Sciences, Campus Talca, Universidad de Talca, Talca, Chile. Electronic address:

Ethylene seems to play a secondary role in non-climacteric strawberry ripening compared to abscisic acid. However, this does not exclude that ethylene can regulate some specific events related to the ripening process. Preliminary experiments of applications of ethylene or its inhibitor 1-MCP to strawberry fruits have reinforced this hypothesis. Here, we reveal some previously non-covered physiological effects of ethylene using an in vitro strawberry ripening system. Fruits of Fragaria chiloensis treated with ethephon at the large green developmental stage showed inhibition of anthocyanin biosynthesis and downregulation of essential anthocyanin biosynthesis genes during the ripening. At the same time, ethylene stimulated lignin biosynthesis and remarkably upregulated the expression of FcPOD27. Since contrasting results have been reported when ethylene was applied at late ripening developmental stages, our findings support the hypothesis of a temporal-specific ethylene role in the ripening of strawberry fruits.
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http://dx.doi.org/10.1016/j.foodchem.2021.129913DOI Listing
April 2021

Genome-Wide B Cell, CD4, and CD8 T Cell Epitopes That Are Highly Conserved between Human and Animal Coronaviruses, Identified from SARS-CoV-2 as Targets for Preemptive Pan-Coronavirus Vaccines.

J Immunol 2021 Apr 28. Epub 2021 Apr 28.

Laboratory of Cellular and Molecular Immunology, Gavin Herbert Eye Institute, School of Medicine, University of California Irvine, Irvine, CA;

Over the last two decades, there have been three deadly human outbreaks of coronaviruses (CoVs) caused by SARS-CoV, MERS-CoV, and SARS-CoV-2, which has caused the current COVID-19 global pandemic. All three deadly CoVs originated from bats and transmitted to humans via various intermediate animal reservoirs. It remains highly possible that other global COVID pandemics will emerge in the coming years caused by yet another spillover of a bat-derived SARS-like coronavirus (SL-CoV) into humans. Determining the Ag and the human B cells, CD4 and CD8 T cell epitope landscapes that are conserved among human and animal coronaviruses should inform in the development of future pan-coronavirus vaccines. In the current study, using several immunoinformatics and sequence alignment approaches, we identified several human B cell and CD4 and CD8 T cell epitopes that are highly conserved in 1) greater than 81,000 SARS-CoV-2 genome sequences identified in 190 countries on six continents; 2) six circulating CoVs that caused previous human outbreaks of the common cold; 3) nine SL-CoVs isolated from bats; 4) nine SL-CoV isolated from pangolins; 5) three SL-CoVs isolated from civet cats; and 6) four MERS strains isolated from camels. Furthermore, the identified epitopes: 1) recalled B cells and CD4 and CD8 T cells from both COVID-19 patients and healthy individuals who were never exposed to SARS-CoV-2, and 2) induced strong B cell and T cell responses in humanized HLA-DR1/HLA-A*02:01 double-transgenic mice. The findings pave the way to develop a preemptive multiepitope pan-coronavirus vaccine to protect against past, current, and future outbreaks.
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http://dx.doi.org/10.4049/jimmunol.2001438DOI Listing
April 2021

Conducting Internet-Based Visits for Onboarding Populations With Limited Digital Literacy to an mHealth Intervention: Development of a Patient-Centered Approach.

JMIR Form Res 2021 Apr 29;5(4):e25299. Epub 2021 Apr 29.

Center for Vulnerable Populations, University of California, San Francisco, San Francisco, CA, United States.

Background: The COVID-19 pandemic has propelled patient-facing research to shift to digital and telehealth strategies. If these strategies are not adapted for minority patients of lower socioeconomic status, health inequality will further increase. Patient-centered models of care can successfully improve access and experience for minority patients.

Objective: This study aims to present the development process and preliminary acceptability of altering in-person onboarding procedures into internet-based, remote procedures for a mobile health (mHealth) intervention in a population with limited digital literacy.

Methods: We actively recruited safety-net patients (English- and Spanish-speaking adults with diabetes and depression who were receiving care at a public health care delivery system in San Francisco, United States) into a randomized controlled trial of text messaging support for physical activity. Because of the COVID-19 pandemic, we modified the in-person recruitment and onboarding procedures to internet-based, remote processes with human support. We conducted a preliminary evaluation of how the composition of the recruited cohort might have changed from the pre-COVID-19 period to the COVID-19 enrollment period. First, we analyzed the digital profiles of patients (n=32) who had participated in previous in-person onboarding sessions prior to the COVID-19 pandemic. Next, we documented all changes made to our onboarding processes to account for remote recruitment, especially those needed to support patients who were not very familiar with downloading apps onto their mobile phones on their own. Finally, we used the new study procedures to recruit patients (n=11) during the COVID-19 social distancing period. These patients were also asked about their experience enrolling into a fully digitized mHealth intervention.

Results: Recruitment across both pre-COVID-19 and COVID-19 periods (N=43) demonstrated relatively high rates of smartphone ownership but lower self-reported digital literacy, with 32.6% (14/43) of all patients reporting they needed help with using their smartphone and installing apps. Significant changes were made to the onboarding procedures, including facilitating app download via Zoom video call and/or a standard phone call and implementing brief, one-on-one staff-patient interactions to provide technical assistance personalized to each patient's digital literacy skills. Comparing recruitment during pre-COVID-19 and COVID-19 periods, the proportion of patients with digital literacy barriers reduced from 34.4% (11/32) in the pre-COVID-19 cohort to 27.3% (3/11) in the COVID-19 cohort. Differences in digital literacy scores between both cohorts were not significant (P=.49).

Conclusions: Patients of lower socioeconomic status have high interest in using digital platforms to manage their health, but they may require additional upfront human support to gain access. One-on-one staff-patient partnerships allowed us to provide unique technical assistance personalized to each patient's digital literacy skills, with simple strategies to troubleshoot patient barriers upfront. These additional remote onboarding strategies can mitigate but not eliminate digital barriers for patients without extensive technology experience.

Trial Registration: Clinicaltrials.gov NCT0349025, https://clinicaltrials.gov/ct2/show/NCT03490253.
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http://dx.doi.org/10.2196/25299DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8086779PMC
April 2021

Daily Motivational Text Messages to Promote Physical Activity in University Students: Results From a Microrandomized Trial.

Ann Behav Med 2021 Apr 19. Epub 2021 Apr 19.

School of Social Welfare, University of California, Berkeley, CA, USA.

Background: Low physical activity is an important risk factor for common physical and mental disorders. Physical activity interventions delivered via smartphones can help users maintain and increase physical activity, but outcomes have been mixed.

Purpose: Here we assessed the effects of sending daily motivational and feedback text messages in a microrandomized clinical trial on changes in physical activity from one day to the next in a student population.

Methods: We included 93 participants who used a physical activity app, "DIAMANTE" for a period of 6 weeks. Every day, their phone pedometer passively tracked participants' steps. They were microrandomized to receive different types of motivational messages, based on a cognitive-behavioral framework, and feedback on their steps. We used generalized estimation equation models to test the effectiveness of feedback and motivational messages on changes in steps from one day to the next.

Results: Sending any versus no text message initially resulted in an increase in daily steps (729 steps, p = .012), but this effect decreased over time. A multivariate analysis evaluating each text message category separately showed that the initial positive effect was driven by the motivational messages though the effect was small and trend-wise significant (717 steps; p = .083), but not the feedback messages (-276 steps, p = .4).

Conclusion: Sending motivational physical activity text messages based on a cognitive-behavioral framework may have a positive effect on increasing steps, but this decreases with time. Further work is needed to examine using personalization and contextualization to improve the efficacy of text-messaging interventions on physical activity outcomes.

Clinicaltrials.gov Identifier: NCT04440553.
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http://dx.doi.org/10.1093/abm/kaab028DOI Listing
April 2021