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Open Access Publications from the University of California

Scholarly Works (9 results)

  • Article
  • Peer Reviewed
UC Davis Previously Published Works (2016)
    Cover page: California's Historic Legacy For Landscape Change, the Wieslander Vegetation Type Maps
    • Article
    • Peer Reviewed
    Information Center for the Environment Publications (2012)

    This paper outlines the production of 270 meter grid‐scale maps for 14 climate and derivative

    hydrologic variables for a region that encompasses the State of California and all the streams

    that flow into it. The paper describes the Basin Characterization Model (BCM), a map‐based,

    mechanistic model used to process the hydrological variables. Three historic and three future

    time periods of 30 years (1911–1940, 1941–1970, 1971–2000, 2010–2039, 2040–2069, and 2070–

    2099) were developed that summarize 180 years of monthly historic and future climate values.

    These comprise a standardized set of fine‐scale climate data that were shared with 14 research

    groups, including the U.S. National Park Service and several University of California groups as

    part of this project. The paper presents three analyses done with the outputs from the Basin

    Characterization Model: trends in hydrologic variables over baseline, the most recent 30‐year

    period; a calibration and validation effort that uses measured discharge values from 139

    streamgages and compares those to Basin Characterization Model‐derived projections of

    discharge for the same basins; and an assessment of the trends of specific hydrological variables

    that links historical trend to projected future change under four future climate projections.

    Overall, increases in potential evapotranspiration dominate other influences in future

    hydrologic cycles. Increased potential evapotranspiration drives decreasing runoff even under

    forecasts with increased precipitation, and drives increased climatic water deficit, which may

    lead to conversion of dominant vegetation types across large parts of the study region, as well

    as have implications for rain‐fed agriculture. The potential evapotranspiration is driven by air

    temperatures, and the Basin Characterization Model permits it to be integrated with a water

    balance model that can be derived for landscapes and summarized by watershed. These results

    show the utility of using a process‐based model with modules representing different

    hydrological pathways that can be interlinked.

      Cover page: Development and application of downscaled hydroclimatic predictor variables for use in climate vulnerability and assessment studies.Creative Commons 'BY' version 4.0 license
      • Article
      • Peer Reviewed
      UCLA Previously Published Works (2015)

      Background

      Mitochondrial dysfunction has been implicated in the pathogenesis of Parkinson's disease (PD), but the cause of this dysfunction is unclear.

      Methods

      Platelet mitochondrial complex I and I/III (nicotinamide adenine dinucleotide cytochrome c reductase, NCCR) activities were measured in early PD patients and matched controls enrolled in a population-based case-control study. Ambient agricultural pesticide exposures were assessed with a geographic information system and California Pesticide Use Registry.

      Results

      In contrast to some previous reports, we found no differences in complex I and I/III activities in subjects with PD and controls. We did find that NCCR activity correlated with subjects' exposure to pesticides known to inhibit mitochondrial activity regardless of their diagnosis.

      Conclusions

      Electron transport chain (ETC) activity is not altered in PD in this well-characterized cohort when compared with community-matched controls but appears to be affected by environmental toxins, such as mitochondria-inhibiting pesticides.
        Cover page: Platelet mitochondrial activity and pesticide exposure in early Parkinson's disease
        • Article
        • Peer Reviewed
        UC San Diego Previously Published Works (2015)

        Purpose

        To explore the cross-sectional and longitudinal relationships between fractional liver fat content, liver volume, and total liver fat burden.

        Methods

        In 43 adults with non-alcoholic steatohepatitis participating in a clinical trial, liver volume was estimated by segmentation of magnitude-based low-flip-angle multiecho GRE images. The liver mean proton density fat fraction (PDFF) was calculated. The total liver fat index (TLFI) was estimated as the product of liver mean PDFF and liver volume. Linear regression analyses were performed.

        Results

        Cross-sectional analyses revealed statistically significant relationships between TLFI and liver mean PDFF (R 2 = 0.740 baseline/0.791 follow-up, P < 0.001 baseline/P < 0.001 follow-up), and between TLFI and liver volume (R 2 = 0.352/0.452, P < 0.001/< 0.001). Longitudinal analyses revealed statistically significant relationships between liver volume change and liver mean PDFF change (R 2 = 0.556, P < 0.001), between TLFI change and liver mean PDFF change (R 2 = 0.920, P < 0.001), and between TLFI change and liver volume change (R 2 = 0.735, P < 0.001).

        Conclusion

        Liver segmentation in combination with MRI-based PDFF estimation may be used to monitor liver volume, liver mean PDFF, and TLFI in a clinical trial.
          • Article
          • Peer Reviewed
          UC San Diego Previously Published Works (2013)

          Unlabelled

          The magnetic resonance imaging-estimated proton density fat fraction (MRI-PDFF) is a novel imaging-based biomarker that allows fat mapping of the entire liver, whereas the magnetic resonance spectroscopy-measured proton density fat fraction (MRS-PDFF) provides a biochemical measure of liver fat in small regions of interest. Cross-sectional studies have shown that MRI-PDFF correlates with MRS-PDFF. The aim of this study was to show the utility of MRI-PDFF in assessing quantitative changes in liver fat through a three-way comparison of MRI-PDFF and MRS-PDFF with the liver histology-determined steatosis grade at two time points in patients with nonalcoholic fatty liver disease (NAFLD). Fifty patients with biopsy-proven NAFLD who participated in a randomized trial underwent a paired evaluation with liver biopsy, MRI-PDFF, and MRS-PDFF at the baseline and 24 weeks. The mean age and body mass index were 47.8 ± 11.7 years and 30.7 ± 6.5 kg/m(2), respectively. MRI-PDFF showed a robust correlation with MRS-PDFF both at week 0 and at week 24 (r = 0.98, P < 0.0001 for both). Cross-sectionally, MRI-PDFF and MRS-PDFF increased with increases in the histology-determined steatosis grade both at week 0 and at week 24 (P < 0.05 for all). Longitudinally, patients who had a decrease (≥ 1%) or increase (≥ 1%) in MRI-PDFF (confirmed by MRS-PDFF) showed a parallel decrease or increase in their body weight and serum alanine aminotransferase and aspartate aminotransferase levels at week 24 (P < 0.05). This small increase or decrease in liver fat could not be quantified with histology.

          Conclusion

          In this longitudinal study, MRI-PDFF correlated well with MRS-PDFF and was more sensitive than the histology-determined steatosis grade in quantifying increases or decreases in the liver fat content. Therefore, it could be used to quantify changes in liver fat in future clinical trials.
            • Article
            • Peer Reviewed
            UC Irvine Previously Published Works (2021)
            Since 2012, studies in mice, rats, and humans have suggested that abnormalities in purinergic signaling may be a final common pathway for many genetic and environmental causes of autism spectrum disorder (ASD). The current study in mice was conducted to characterize the bioenergetic, metabolomic, breathomic, and behavioral features of acute hyperpurinergia triggered by systemic injection of the purinergic agonist and danger signal, extracellular ATP (eATP). Responses were studied in C57BL/6J mice in the maternal immune activation (MIA) model and controls. Basal metabolic rates and locomotor activity were measured in CLAMS cages. Plasma metabolomics measured 401 metabolites. Breathomics measured 98 volatile organic compounds. Intraperitoneal eATP dropped basal metabolic rate measured by whole body oxygen consumption by 74% ± 6% (mean ± SEM) and rectal temperature by 6.2˚ ± 0.3˚C in 30 minutes. Over 200 metabolites from 37 different biochemical pathways where changed. Breathomics showed an increase in exhaled carbon monoxide, dimethylsulfide, and isoprene. Metabolomics revealed an acute increase in lactate, citrate, purines, urea, dopamine, eicosanoids, microbiome metabolites, oxidized glutathione, thiamine, niacinamide, and pyridoxic acid, and decreased folate-methylation-1-carbon intermediates, amino acids, short and medium chain acyl-carnitines, phospholipids, ceramides, sphingomyelins, cholesterol, bile acids, and vitamin D similar to some children with ASD. MIA animals were hypersensitive to postnatal exposure to eATP or poly(IC), which produced a rebound increase in body temperature that lasted several weeks before returning to baseline. Acute hyperpurinergia produced metabolic and behavioral changes in mice. The behaviors and metabolic changes produced by ATP injection were associated with mitochondrial functional changes that were profound but reversible.
              Cover page: Metabolic and behavioral features of acute hyperpurinergia and the maternal immune activation mouse model of autism spectrum disorder
              • Article
              • Peer Reviewed
              UC San Diego Previously Published Works (2012)

              Unlabelled

              Bile acid sequestrants (BAS) lower plasma low density lipoprotein levels and improve glycemic control. Colestimide, a BAS, has been claimed by computed tomography to reduce liver fat. Therefore, we examined the efficacy of colesevelam, a potent BAS, to decrease liver fat in patients with biopsy-proven nonalcoholic steatohepatitis (NASH). Liver fat was measured by a novel magnetic resonance imaging (MRI) technique, the proton-density-fat-fraction (PDFF), as well as by conventional MR spectroscopy (MRS). Fifty patients with biopsy-proven NASH were randomly assigned to either colesevelam 3.75 g/day orally or placebo for 24 weeks. The primary outcome was change in liver fat as measured by MRI-PDFF in colocalized regions of interest within each of the nine liver segments. Compared with placebo, colesevelam increased liver fat by MRI-PDFF in all nine segments of the liver with a mean difference of 5.6% (P = 0.002). We cross-validated the MRI-PDFF-determined fat content with that assessed by colocalized MRS; the latter showed a mean difference of 4.9% (P = 0.014) in liver fat between the colesevelam and the placebo arms. MRI-PDFF correlated strongly with MRS-determined hepatic fat content (r(2) = 0.96, P < 0.0001). Liver biopsy assessment of steatosis, cellular injury, and lobular inflammation did not detect any effect of treatment.

              Conclusion

              Colesevelam increases liver fat in patients with NASH as assessed by MRI as well as MRS without significant changes seen on histology. Thus, MRI and MRS may be better than histology to detect longitudinal changes in hepatic fat in NASH. Underlying mechanisms and whether the small MR-detected increase in liver fat has clinical consequences is not known.
                Cover page: Effect of colesevelam on liver fat quantified by magnetic resonance in nonalcoholic steatohepatitis: A randomized controlled trial
                • Article
                • Peer Reviewed
                UC Davis Previously Published Works (2022)
                Invasive fungal infections continue to increase as at-risk populations expand. The high associated morbidity and mortality with fungal diseases mandate the continued investigation of novel antifungal agents and diagnostic strategies that include surrogate biomarkers. Biologic markers of disease are useful prognostic indicators during clinical care, and their use in place of traditional survival end points may allow for more rapid conduct of clinical trials requiring fewer participants, decreased trial expense, and limited need for long-term follow-up. A number of fungal biomarkers have been developed and extensively evaluated in prospective clinical trials and small series. We examine the evidence for these surrogate biomarkers in this review and provide recommendations for clinicians and regulatory authorities.
                  Cover page: Noninvasive Testing and Surrogate Markers in Invasive Fungal Diseases
                  • Article
                  • Peer Reviewed
                  UC Davis Previously Published Works (2021)
                  The global burden of the endemic mycoses (blastomycosis, coccidioidomycosis, emergomycosis, histoplasmosis, paracoccidioidomycosis, sporotrichosis, and talaromycosis) continues to rise yearly and these infectious diseases remain a leading cause of patient morbidity and mortality worldwide. Management of the associated pathogens requires a thorough understanding of the epidemiology, risk factors, diagnostic methods and performance characteristics in different patient populations, and treatment options unique to each infection. Guidance on the management of these infections has the potential to improve prognosis. The recommendations outlined in this Review are part of the "One World, One Guideline" initiative of the European Confederation of Medical Mycology. Experts from 23 countries contributed to the development of these guidelines. The aim of this Review is to provide an up-to-date consensus and practical guidance in clinical decision making, by engaging physicians and scientists involved in various aspects of clinical management.
                    Cover page: Global guideline for the diagnosis and management of the endemic mycoses: an initiative of the European Confederation of Medical Mycology in cooperation with the International Society for Human and Animal Mycology
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