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Open Access Publications from the University of California

Scholarly Works (10 results)

  • Thesis
  • Peer Reviewed
UC San Diego Electronic Theses and Dissertations (2020)

Background: Persons who inject drugs (PWID) are at increased risk for infectious diseases and overdose, and need access to primary care and substance use disorder (SUD) services. Yet, PWID historically have avoided and delayed seeking care, in part due to lacking insurance coverage for services they need and an availability of these services at local clinics. The Affordable Care Act (ACA) made insurance mandatory and included SUD services as an essential health benefit.Objectives: This dissertation research sought to examine the impact of the implementation of the ACA on the use of SUD treatment (Chapter 2) and primary care services (Chapter 3) among PWID in San Diego. It also sought to understand the changes in offering of SUD services at community and free primary care clinics after this health reform was implemented (Chapter 4). Methods: This dissertation is comprised of three papers assessing different aspects of health service use among PWID in San Diego County. Papers one and two (Chapters 2 and 3) used data from a longitudinal cohort study of 576 PWID in San Diego (STAHR 2 Study) to determine the impact of the ACA on the use of SUD treatment and the use of primary care services, respectively. Paper three (Chapter 3) used facility-level data on community and free primary care clinics in San Diego County from the California Office of Statewide Health Planning and Development to understand changes in offering of SUD services at these clinics after the ACA compared to before. Results: For paper one (Chapter 2), there was an increase (12%) in use of SUD treatment after the ACA compared to before, with a similar increase (10%) in insurance coverage. The ACA was associated with greater use of SUD treatment among PWID and the strength of this association was not impacted by insurance coverage. For paper two (Chapter 3), there was an increase (4%) in primary care use after the ACA compared to before, with a much larger increase (24%) in those who had insurance coverage. The ACA was associated with greater use of primary care services among PWID and the strength of the association was not entirely explained by an increase in insurance coverage. Paper three (Chapter 4) showed an decrease of 7% in the number of community and primary care clinics that offered SUD services after the ACA compared to before, but an increase in the proportion of patients covered by Medi-Cal and had contact with a substance abuse counselor. Conclusion: These findings suggest that the ACA may have been an effective health policy for increasing access and use of essential health services among PWID in San Diego, and for bolstering SUD services in community and free primary care clinics.

    Cover page: Essays on Healthcare Utilization in Persons Who Inject Drugs
    • Article
    • Peer Reviewed
    UC San Diego Previously Published Works (2022)

    Background

    There is an expanding unregulated market for a psychotropic compound called ∆8-Tetrahydrocannabinol (delta-8-THC) that is being derived from hemp, but there are no empirical estimates of public interest in this compound.

    Methods

    To measure public interest, we obtained yearly Google query fractions (QFs) that mentioned delta-8-THC (i.e., "delta 8," "delta-8," or "Δ8") for the past decade (from January 2011 through August 2021) for every country and territory in the world and every state in the United States (US) from Google Trends. We also obtained the same trends for the last complete month of data for all US states (July 2021) to compare across cannabis use policies. We summarized QFs across years, countries, US states and cannabis policies in US states using linear regression, means and ratios. We estimated raw search counts for the US using comscore.com.

    Results

    The global rate of delta-8-THC searches was stable between 2011 and 2019 before increasing by 257.0% from 2019 to 2020 and 705.0% from 2020 to 2021. In 2021, the rate of delta-8-THC searches in the US was at least 10 times higher than the rates in other countries or territories. In absolute terms, there were 22.3 million delta-8-THC searches in the US in the first 8 months of 2021 alone. Increases in delta-8-THC searches from 2020 to 2021 occurred in all 50 US states and the District of Columbia (Mean 854.2%; range = 256.4% - 2831.2%) but continued to vary substantially between states in 2021. In July 2021, the legal status of delta-9-THC use across US states explained 49.0% of the variance in delta-8-THC QFs between US states (R2 = 0.490; p < 0.001) and was inversely associated, where delta-8-THC QFs were higher in jurisdictions with stricter cannabis use policies.

    Conclusion

    Public interest in delta-8-THC increased rapidly in 2020 and 2021 and was particularly high in US states that restricted delta-9-THC use. Jurisdictions should clarify whether delta-8-THC can be sold as a hemp product.
      Cover page: Public interest in ∆8-Tetrahydrocannabinol (delta-8-THC) increased in US states that restricted ∆9-Tetrahydrocannabinol (delta-9-THC) use
      • Article
      • Peer Reviewed
      UC San Diego Previously Published Works (2018)
        Cover page: The Potential Influence of Regulatory Environment for E-Cigarettes on the Effectiveness of E-Cigarettes for Smoking Cessation: Different Reasons to Temper the Conclusions From Inadequate Data
        • Article
        • Peer Reviewed
        UC San Diego Previously Published Works (2018)
        Objective: In this paper, we examine whether a slowdown in implementing tobacco control policies in California after 2000 influenced trends in smoking behavior. Methods: We assessed the strength of state tobacco control policies using excise tax data (1990-2014), tobacco control expenditures per capita, and workplace and home smoking restrictions (from the Tobacco Use Supplement of the Current Population Survey, 1992-2015). Smoking prevalence was assessed with the National Health Interview Survey, 1985-2015. We compared trends between California and the rest of the US using split regression models with a knot at 2000. Results: Throughout the 1990s, compared to the rest of the US, California had higher cigarette excise taxes, higher expenditures on tobacco control, more smoke-free workplaces, and more smokers with smoke-free homes. Except for smoke-free homes, these differences disappeared after 2000. During the 1990s, smoking prevalence declined much faster in California than in the rest of the US, but the decline slowed significantly after 2000. Conclusions: Smoking prevalence is sensitive to continued implementation of tobacco control policies.
          Cover page: Did Slowdown on Taxes and Program Impact California's Smoking Decline?
          • Article
          • Peer Reviewed
          UC San Diego Previously Published Works (2017)

          Background

          The prevalence of HIV and Hepatitis C Virus (HCV) are significantly lower among people who inject drugs (PWID) in San Diego, CA, USA compared with PWID in Tijuana, Mexico, located directly across the border. We investigated associations between cross-border injection drug use (IDU), HIV and HCV seroprevalence and engagement in injecting risk behaviours while on each side of the border.

          Methods

          Using baseline interviews and serologic testing data from STAHR II, a longitudinal cohort study of PWID in San Diego, bivariate and multivariable logistic regression analyses examined associations between recent (past six months) cross-border IDU and HIV and HCV antibody seropositivity, socio-demographics, drug use characteristics, and participants' connections to, and perceptions about Mexico. Chi-squared tests and McNemar tests examined associations between cross-border IDU and injecting risk behaviours.

          Results

          Of the 567 participants (93% U.S.-born, 73% male, median age 45 years), 86 (15%) reported recent cross-border IDU. Cross-border IDU was not associated with HIV (OR: 0.85, 95% CI: 0.37-1.95) or HCV seropositivity (OR: 1.01, 95% CI: 0.62-1.65). Age, identifying as Hispanic or Latino/a, and being concerned about risk of violence when travelling to Mexico were independently associated with decreased odds of recent cross-border IDU. Injecting cocaine at least weekly, having ever lived in Mexico and knowing PWID who reside in Mexico were associated with increased odds of recent cross-border IDU. PWID who reported cross-border IDU were significantly less likely to engage in receptive needle sharing, equipment sharing, and public injection while in Mexico compared with in San Diego (all p<0.001).

          Conclusion

          Prevalence of HIV and HCV infection was similar among PWID who had and had not injected in Mexico, possibly due to practising safer injecting while in Mexico. Research is needed to elucidate contextual factors enabling U.S. PWID to inject safely while in Mexico.
            • Article
            • Peer Reviewed
            UCLA Previously Published Works (2019)
            It is well-understood that many bacteria have evolved to survive catastrophic events using a variety of mechanisms, which include expression of stress-response genes, quiescence, necrotrophy, and metabolic advantages obtained through mutation. However, the dynamics of individuals leveraging these abilities to gain a competitive advantage in an ecologically complex setting remain unstudied. In this study, we observed the saliva microbiome throughout the ecological perturbation of long-term starvation, allowing only the species best equipped to access and use the limited resources to survive. During the first several days, the community underwent a death phase that resulted in a ∼50-100-fold reduction in the number of viable cells. Interestingly, after this death phase, only three species, Klebsiella pneumoniae, Klebsiella oxytoca, and Providencia alcalifaciens, all members of the family Enterobacteriaceae, appeared to be transcriptionally active and recoverable. Klebsiella are significant human pathogens, frequently resistant to multiple antibiotics, and recently, ectopic colonization of the gut by oral Klebsiella was documented to induce dysbiosis and inflammation. MetaOmics analyses provided several leads for further investigation regarding the ecological success of the Enterobacteriaceae. The isolates accumulated single nucleotide polymorphisms in known growth advantage in stationary phase alleles and produced natural products closely resembling antimicrobial cyclic depsipeptides. The results presented in this study suggest that pathogenic Enterobacteriaceae persist much longer than their more benign neighbors in the salivary microbiome when faced with starvation. This is particularly significant, given that hospital surfaces contaminated with oral fluids, especially sinks and drains, are well-established sources of outbreaks of drug-resistant Enterobacteriaceae.
              Cover page: Klebsiella and Providencia emerge as lone survivors following long-term starvation of oral microbiota
              • Article
              • Peer Reviewed
              UC San Diego Previously Published Works (2020)

              Importance

              Use of cannabidiol (CBD) has markedly increased in the past 5 years, concurrent with marketing claims that over-the-counter CBD can be used to treat almost any health condition. However, the reasons why individuals use CBD remain unclear.

              Objective

              To assess whether individuals are using CBD for diagnosable conditions that have evidence-based therapies.

              Design, setting, and participants

              This case series assessed claimed treatment applications reported by CBD users in public testimonials shared on the Reddit forum r/CBD. The r/CBD forum was selected because it includes a large, naturally occurring sample of 104 917 registered individuals who publicly discuss their experiences using CBD. All r/CBD posts were obtained from January 1, 2014, through August 31, 2019. A random sample of posts was drawn (n = 3000) and filtered to include posts in which self-identified CBD users testified why they take CBD (n = 376).

              Exposures

              Self-reported use of CBD for medicinal purposes.

              Main outcomes and measures

              Cannabidiol testimonials were divided into 11 subcategories corresponding with the condition's medical subspecialty and 2 subcategories corresponding with wellness benefits. Posts were allowed to receive more than 1 label.

              Results

              Of the 376 posts labeled as testimonials, 90.0% (95% CI, 86.8%-92.8%) of testimonials claimed that CBD treated the individual's diagnosable conditions. Psychiatric conditions (eg, autism or depression) were the most frequently cited subcategory, mentioned in 63.9% (95% CI, 59.0%-69.1%) of testimonials, followed by orthopedic (26.4%; 95% CI, 21.8%-31.1%), sleep (14.6%; 95% CI, 11.3%-18.5%), and neurological (6.9%; 95% CI, 4.4%-9.6%) conditions. Testimonials also claimed that CBD treated gastroenterological conditions (3.9%; 95% CI, 1.9%-6.1%), as well as addiction, cardiological, dermatological, ophthalmological, oral health, and sexual health conditions (<2.0% each). By contrast, just 29.5% (95% CI, 24.8%-34.2%) of testimonies claimed any wellness benefit, with most citing mental wellness (eg, "quieting my mind") (29.5% [95% CI, 24.2%-34.4%]); 1.4% (95% CI, 0.3%-2.8%) claimed a physical wellness benefit (eg, "exercise performance").

              Conclusions and relevance

              The findings of this case series suggest a need for regulation of factors associated with CBD being used to treat diagnosable conditions, engagement of health care professionals with patients on their potential CBD use, and implementation of public health campaigns that encourage the public to seek treatment advice from health care professionals regarding evidence-based therapies.
                • Article
                • Peer Reviewed
                UC San Diego Previously Published Works (2018)

                Background

                In the 1990s, California led the USA in state-level tobacco control strategies. However, after 2000, California lost ground on cigarette taxes, although it maintained higher levels of smoke-free homes among smokers.

                Methods

                Trends in per capita cigarette consumption were assessed through taxed sales data and from self-report in repeated national cross-sectional surveys. Linear regressions identified changes in trends after year 2000 separately for California and the rest of the USA. Using data from each state, a linear regression tested the association between different tobacco control strategies and per capita consumption. Change in self-reported per capita consumption was partitioned into contributions associated with initiation, quitting and reduction in cigarette consumption level.

                Results

                Both taxed cigarette sales and per capita consumption declined rapidly in the USA from 1985 to 2015. Declines were particularly fast in California before 2000 but slowed thereafter. In 2014, per capita consumption in California was 29.4 packs/adult/year, but 90% higher in the rest of the USA. Modelling state-level data, every $1 increase in cigarette taxes reduced consumption by 4.8 (95% CI 2.9 to 6.8) packs/adult/year. Every 5% increase in the proportion of smokers with smoke-free homes reduced consumption by 8.0 (95% CI 7.0 to 8.9) packs/adult/year. The different patterns in California and the rest of the USA are at least partially explained by these two variables. The slow down in per capita consumption in California can be attributed to changes in initiation, quitting and especially smokers reducing their consumption level.

                Conclusions

                Tobacco control strategies need to be continually updated to maintain momentum towards a smoke-free society.
                  Cover page: Tobacco control in California compared with the rest of the USA: trends in adult per capita cigarette consumption
                  • Article
                  • Peer Reviewed
                  UC San Diego Previously Published Works (2019)
                  Three cigarette smoking behaviors influence lung cancer rates: how many people start, the amount they smoke, and the age they quit. California has reduced smoking faster than the rest of the United States and trends in these three smoking behaviors should inform lung cancer trends. We examined trends in smoking behavior (initiation, intensity, and quitting) in California and the rest of United States by regression models using the 1974-2014 National Health Interview Surveys (n = 962,174). Lung cancer mortality data for 1970-2013 was obtained from the National Surveillance, Epidemiology, and End Results (SEER) Program. Among those aged 18 to 35 years, California had much larger declines than the rest of the United States in smoking initiation and intensity, and increased quitting. In 2012-2014, among this age group, only 18.6% [95% confidence interval (CI), 16.8%-20.3%] had ever smoked; smokers consumed only 6.3 cigarettes/day (95% CI, 5.6-7.0); and 45.7% (95% CI, 41.1%-50.4%) of ever-smokers had quit by age 35. Each of these metrics was at least 24% better than in the rest of the United States. There was no marked California effect on quitting or intensity among seniors. From 1986 to 2013, annual lung cancer mortality decreased more rapidly in California and by 2013 was 28% lower (62.6 vs. 87.5/100,000) than in the rest of the United States. California's tobacco control efforts were associated with a major reduction in cigarette smoking among those under age 35 years. These changes will further widen the lung cancer gap that already exists between California and the rest of the United States.
                    Cover page: Trends in lung cancer and cigarette smoking: California compared to the rest of the United States
                    • Article
                    • Peer Reviewed
                    UC Berkeley Previously Published Works (2012)
                    Methanococcus maripaludis grown syntrophically with Desulfovibrio vulgaris was compared with M. maripaludis monocultures grown under hydrogen limitation using transcriptional, proteomic and metabolite analyses. These measurements indicate a decrease in transcript abundance for energy-consuming biosynthetic functions in syntrophically grown M. maripaludis, with an increase in transcript abundance for genes involved in the energy-generating central pathway for methanogenesis. Compared with growth in monoculture under hydrogen limitation, the response of paralogous genes, such as those coding for hydrogenases, often diverged, with transcripts of one variant increasing in relative abundance, whereas the other was little changed or significantly decreased in abundance. A common theme was an apparent increase in transcripts for functions using H(2) directly as reductant, versus those using the reduced deazaflavin (coenzyme F(420)). The greater importance of direct reduction by H(2) was supported by improved syntrophic growth of a deletion mutant in an F(420)-dependent dehydrogenase of M. maripaludis. These data suggest that paralogous genes enable the methanogen to adapt to changing substrate availability, sustaining it under environmental conditions that are often near the thermodynamic threshold for growth. Additionally, the discovery of interspecies alanine transfer adds another metabolic dimension to this environmentally relevant mutualism.
                      Cover page: Functional responses of methanogenic archaea to syntrophic growth
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