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Open Access Publications from the University of California

Recent Work

The Research Grants Program Office (RGPO) oversees a broad grantmaking portfolio of nearly $65 million a year to support research that is critical to California, the nation and the world. RGPO programs enhance UC’s research capacity and excellence, which helps attract top faculty, graduate students, government funding and companies to our state. These grants also enable researchers and community agencies to collaborate and solve the most pressing problems in the state. RGPO also provides grants for training undergraduates, graduate and postdoctoral researchers, whose work will benefit California communities. 

A bioactive material with dual integrin-targeting ligands regulates specific endogenous cell adhesion and promotes vascularized bone regeneration in adult and fetal bone defects.

(2023)

Significant progress has been made in designing bone materials capable of directing endogenous cells to promote vascularized bone regeneration. However, current strategies lack regulation of the specific endogenous cell populations for vascularized bone regeneration, thus leading to adverse tissue formation and decreased regenerative efficiency. Here, we engineered a biomaterial to regulate endogenous cell adhesion and promote vascularized bone regeneration. The biomaterial works by presenting two synthetic ligands, LLP2A and LXW7, explicitly targeting integrins α4β1 and αvβ3, respectively, expressed on the surfaces of the cells related to bone formation and vascularization, such as mesenchymal stem cells (MSCs), osteoblasts, endothelial progenitor cells (EPCs), and endothelial cells (ECs). In vitro, the LLP2A/LXW7 modified biomaterial improved the adhesion of MSCs, osteoblasts, EPCs, and ECs via integrin α4β1 and αvβ3, respectively. In an adult rat calvarial bone defect model, the LLP2A/LXW7 modified biomaterial enhanced bone formation and vascularization by synergistically regulating endogenous cells with osteogenic and angiogenic potentials, such as DLX5+ cells, osteocalcin+ cells, CD34+/CD45- cells and CD31+ cells. In a fetal sheep spinal bone defect model, the LLP2A/LXW7 modified biomaterial augmented bone formation and vascularization without any adverse effects. This innovative biomaterial offers an off-the-shelf, easy-to-use, and biologically safe product suitable for vascularized bone regeneration in both fetal and adult disease environments.

Telemedicine implementation and use in community health centers during COVID-19: Clinic personnel and patient perspectives.

(2022)

In March 2020, federal and state telehealth policy changes catalyzed telemedicine adoption and use in community health centers. There is a dearth of evidence on telemedicine implementation and use in these safety net settings and a lack of information reflecting the perspectives of patients with limited English proficiency. We conducted in-depth interviews with clinic personnel and patients during the pandemic in two federally qualified health centers that primarily serve Chinese and Latino immigrants. Twenty-four interviews (clinic personnel ​= ​15; patients who primarily speak a language other than English ​= ​9) were completed remotely between December 2020 and April 2021. Interview scripts included questions about their telemedicine experiences, technology, resources and needs, barriers, facilitators, language access, and continued use, with a brief socio-demographic survey. Data analyses involved a primarily deductive approach and thematic analysis of transcript content. Both FQHCs adopted telemedicine in a few weeks and transitioned primarily to video and audio-only visits within two months. Findings reveal third-party language interpretation services were challenging to integrate into telemedicine video visits. Bilingual personnel who provided language concordant care were seen as essential for efficient and high-quality patient telemedicine experiences. Audio-only visits were of particular benefit to reach patients of older age, with limited English proficiency, and with limited digital literacy. Continued use of telemedicine is contingent on reimbursement policy decisions and interventions to increase patient digital literacy and technological resources. Results highlight the importance of reimbursing audio-only visits post-pandemic and investing in efforts to improve the quality of language services in telemedicine encounters.

A systematic method for selecting molecular descriptors as features when training models for predicting physiochemical properties

(2022)

Machine learning has proven to be a powerful tool for accelerating biofuel development. Although numerous models are available to predict a range of properties using chemical descriptors, there is a trade-off between interpretability and performance. Neural networks provide predictive models with high accuracy at the expense of some interpretability, while simpler models such as linear regression often lack in accuracy. In addition to model architecture, feature selection is also critical for developing interpretable and accurate predictive models. We present a method for systematically selecting molecular descriptor features and developing interpretable machine learning models without sacrificing accuracy. Our method simplifies the process of selecting features by reducing feature multicollinearity and enables discoveries of new relationships between global properties and molecular descriptors. To demonstrate our approach, we developed models for predicting melting point, boiling point, flash point, yield sooting index, and net heat of combustion with the help of the Tree-based Pipeline Optimization Tool (TPOT). For training, we used publicly available experimental data for up to 8351 molecules. Our models accurately predict various molecular properties for organic molecules (mean absolute percent error (MAPE) ranges from 3.3% to 10.5%) and provide a set of features that are well-correlated to the property. This method enables researchers to explore sets of features that significantly contribute to the prediction of the property, offering new scientific insights. To help accelerate early stage biofuel research and development, we also integrated the data and models into a open-source, interactive web tool.

Cover page of Pacific Islanders in the Era of COVID-19: an Overlooked Community in Need.

Pacific Islanders in the Era of COVID-19: an Overlooked Community in Need.

(2022)

Background

Pacific Islanders (PIs), an indigenous, diverse population in the USA, have endured generational burdens of Western colonization and institutional racism that placed this population at socioeconomic and health disadvantages, such as in poverty, chronic disease, and now COVID-19. However, little is known about the impact of COVID-19 on this historically disadvantaged population. This study assessed the extent US PIs have been adversely affected by COVID-19 across the 50 states.

Methods

Using state-level national data as of September 9th, 2020, we conducted a secondary-data analysis of COVID-19 cases and deaths in PIs relative to their population representation and other racial groups, case odds ratios, and age-adjusted standard mortality ratios.

Key results

Only 46% of states reported PI cases and 36% of states reported PI deaths. Of 23 states with available data on PIs, PIs were overrepresented in COVID-19 cases and deaths relative to their population representation in 21 and 14 states, respectively. The proportion of COVID-19 cases and deaths to the PI population was highest among all racial groups in 15 and 9 states, respectively. PIs had higher odds of exposure to COVID-19 than Whites in 21 of 23 states, and higher number of observed deaths than expected in 6 of 7 states with available PI data.

Conclusions

Engaging PI community-based and faith-based organizations in medical and public health outreach efforts, health workforce employment and training programs, along with granular data collection and reporting, are vital to mitigate the disproportionate effects of COVID-19 on this population.

A Systematic Review up to 2018 of HIV and Associated Factors Among Criminal Justice-Involved (CJI) Black Sexual and Gender Minority Populations in the United States (US).

(2022)

Black men who have sex with men (BMSM) and Black transgender women (BTW) are impacted by dual epidemics of HIV and incarceration. We advanced understanding of the relationship between criminal justice involvement, HIV, and other key HIV-related characteristics among these key populations in the US. We conducted a systematic review up to 2018 and 47 articles met the inclusion criteria of scientific publications involving quantitative findings of US-based HIV-related studies focused on criminal justice-involved (CJI) BMSM and BTW. Overall, there was a dearth of studies focused specifically on BTW. Criminal justice involvement was relatively high among BMSM and BTW and more pronounced among BTW. The current evidence favors no association between incarceration and HIV acquisition among BMSM with limited information about BTW. Criminal justice involvement was associated with a greater likelihood of STIs among BMSM with mixed results for sexual risk behaviors. Criminal justice settings served as an important venue for HIV testing/diagnosis for both BMSM and BTW. However, these settings were not conducive for subsequent stages of the HIV care continuum. Studies pointed to an independent association between criminal justice involvement, substance use, housing instability, and greater odds of incarceration among BMSM who were unemployed and had limited education. Future incarceration was associated with high levels of perceived racism among BMSM. Among young BMSM, high network criminal justice prevalence was also associated with sexual risk behaviors, poorer mental health outcomes, drug use, and housing instability. CJI BMSM and BTW represent a critical subpopulation to end the HIV epidemic in the US.

Cover page of Enabling Design Space Exploration for RISC-V Secure Compute Environments

Enabling Design Space Exploration for RISC-V Secure Compute Environments

(2022)

Cycle-level architectural simulation of Trusted Execution Environ- ments (TEEs) can enable extensive design space exploration of these secure architectures. Existing architectural simulators which sup- port TEEs are either based on hardware-level implementations or abstract analytic models. In this paper, we describe the implementation of the gem5 models necessary to run and evaluate the RISC- V-based open source TEE, Keystone, and we discuss how this simulation environment opens new avenues for designing and studying these trusted environments. We show that the Keystone simulations on gem5 exhibit similar performance as the previous hardware eval- uations of Keystone. We also describe three simple example use cases (understanding the reason of trusted execution slowdown, performance of memory encryption, and micro-architecture impact on trusted execution performance) to demonstrate how the ability to simulate TEEs can provide useful information about their behavior in the existing form and also with enhanced designs.