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Open Access Publications from the University of California

Scholarly Works (11 results)

  • Article
UCLA Criminal Justice Law Review, Volume 4, Issue 1 (2020)
    Cover page: If We Only Knew the Cost: Scratching the Surface on How Much it Costs to Assess and Collect Court Imposed Criminal Fees and Fines
    • Article
    • Peer Reviewed
    UC Davis Previously Published Works (2013)
    Abstract Background Beyond the core symptoms of autism spectrum disorder (ASD), associated symptoms of anxiety can cause substantial impairment for individuals affected by ASD and those who care for them. Methods We utilized a potentiated startle paradigm with a puff of air to the neck as the unconditioned stimulus in order to investigate differences between response to cued fear and contextual anxiety among cognitively able adolescents diagnosed with ASD and an age- and IQ-matched typically developing group. Results In a threat-modulated startle paradigm, response patterns to neutral, predictable, and unpredictable conditions were comparable across typically developing and ASD youth in terms of startle response magnitude and latency. However, the ASD group showed significantly greater absolute startle responsivity at baseline and throughout the experiment, suggesting possibly enhanced general sensitivity to threatening contexts. The ASD group, but not the control group, demonstrated moderate to strong negative correlations between psychophysiological response to unpredictable threats (uncertainty) and questionnaire measures of generalized anxiety, intolerance of uncertainty, and repetitive behavior. Conclusions Our data suggest enhanced general reactivity among the ASD group, possibly reflecting greater sensitivity to the threatening context of the startle paradigm. Associations with the response to uncertainty may help explain shared neurobehavioral mechanisms in ASD and anxiety. This task can provide useful targets for future neuroimaging and genetics studies as well as specific avenues for intervention. We emphasize the importance of further basic and clinical research into links among these important constructs.
      Cover page: A potentiated startle study of uncertainty and contextual anxiety in adolescents diagnosed with autism spectrum disorder
      • Article
      • Peer Reviewed
      SSOE Research Symposium Dean's Awards (2016)

      Background:  The ever expanding modern internet is stored on huge banks of hard drives called data centers. With the massive growth of data storage needs, a modern engineering challenge is to reduce the carbon footprint of data centers by powering them greenly.

      Faculty Advisors: Dr. Jacob Brouwer -  Department of Mechanical & Aerospace Engineering              jbrouwer@uci.edu

        Cover page: Fuel Cell Data Center: Renewably Powering the Internet
        • Article
        • Peer Reviewed
        Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health, Volume 21, Issue 6 (2020)

        Introduction: Prior research shows that physicians in training are at risk for drowsy driving following their clinical duties, which may put them in danger of experiencing adverse driving events. This study explores the relationship between sleepiness, overall sleep hygiene, level of training, and adverse driving events following an overnight shift in emergency medicine (EM) residents.

        Methods: Throughout the 2018-2019 academic year, 50 EM residents from postgraduate years 1–4 completed self-administered surveys regarding their sleepiness before and after their drive home following an overnight shift, any adverse driving events that occurred during their drive home, and their overall sleep hygiene.

        Results: Fifty out of a possible 57 residents completed the survey for a response rate of 87.7%. Sleepiness was significantly associated with adverse driving events (beta = 0.31; P < .001). Residents with high sleepiness levels reported significantly more adverse driving events. Residents reported significantly higher sleepiness levels after completing their drive home (mean = 7.04, standard deviation [SD] = 1.41) compared to sleepiness levels before driving home (mean = 5.58, SD = 1.81). Residency training level was significantly associated with adverse driving events (beta = -0.59, P < .01). Senior residents reported significantly fewer adverse driving events compared to junior residents.

        Conclusion: Emergency physicians in training are at risk for drowsy driving-related motor vehicle crashes following overnight work shifts. Trainees of all levels underestimated their true degree of sleepiness prior to initiating their drive home, while junior residents were at higher risk for adverse driving events.

        • 3 supplemental files
        Cover page: The Association of Sleep Hygiene and Drowsiness with Adverse Driving Events in Emergency Medicine ResidentsCreative Commons 'BY' version 4.0 license
        • Article
        • Peer Reviewed
        UC Irvine Previously Published Works (2014)
        Across species, kin bond together to promote survival. We sought to understand the dyadic effect of exclusion by kin (as opposed to non-kin strangers) on brain activity of the mother and her child and their subjective distress. To this end, we probed mother-child relationships with a computerized ball-toss game Cyberball. When excluded by one another, rather than by a stranger, both mothers and children exhibited a significantly pronounced frontal P2. Moreover, upon kin rejection versus stranger rejection, both mothers and children showed incremented left frontal positive slow waves for rejection events. Children reported more distress upon exclusion than their own mothers. Similar to past work, relatively augmented negative frontal slow wave activity predicted greater self-reported ostracism distress. This effect, generalized to the P2, was limited to mother- or child-rejection by kin, with comparable magnitude of effect across kin identity (mothers vs. children). For both mothers and children, the frontal P2 peak was significantly pronounced for kin rejection versus stranger rejection. Taken together, our results document the rapid categorization of social signals as kin relevant and the specificity of early and late neural markers for predicting felt ostracism.
          Cover page: Kin rejection: social signals, neural response and perceived distress during social exclusionCreative Commons 'BY' version 4.0 license
          • Article
          • Peer Reviewed
          UC San Francisco Previously Published Works (2017)
          The mechanistic underpinnings of the complex process of plant polysaccharide biosynthesis are poorly understood, largely because of the resistance of glycosyltransferase (GT) enzymes to structural characterization. In Arabidopsis thaliana, a glycosyl transferase family 37 (GT37) fucosyltransferase 1 (AtFUT1) catalyzes the regiospecific transfer of terminal 1,2-fucosyl residues to xyloglucan side chains - a key step in the biosynthesis of fucosylated sidechains of galactoxyloglucan. We unravel the mechanistic basis for fucosylation by AtFUT1 with a multipronged approach involving protein expression, X-ray crystallography, mutagenesis experiments and molecular simulations. Mammalian cell culture expressions enable the sufficient production of the enzyme for X-ray crystallography, which reveals the structural architecture of AtFUT1 in complex with bound donor and acceptor substrate analogs. The lack of an appropriately positioned active site residue as a catalytic base leads us to propose an atypical water-mediated fucosylation mechanism facilitated by an H-bonded network, which is corroborated by mutagenesis experiments as well as detailed atomistic simulations.
            Cover page: Structural, mutagenic and in silico studies of xyloglucan fucosylation in Arabidopsis thaliana suggest a water‐mediated mechanism
            • Article
            • Peer Reviewed
            UC Davis Previously Published Works (2020)
            The Continuous Assessment of Interpersonal Dynamics (CAID) is a method in which trained observers continuously code the dominance and warmth of individuals who interact with one another in dyads. This method has significant promise for assessing dynamic interpersonal processes. The purpose of this study was to examine the impact of individual sex, dyadic familiarity, and situational conflict on patterns of interpersonal warmth, dominance, and complementarity as assessed via CAID. We used six samples with 603 dyads, including two samples of unacquainted mixed-sex undergraduates interacting in a collaborative task, two samples of couples interacting in both collaborative and conflict tasks, and two samples of mothers and children interacting in both collaborative and conflict tasks. Complementarity effects were robust across all samples, and individuals tended to be relatively warm and dominant. Results from multilevel models indicated that women were slightly warmer than men, whereas there were no sex differences in dominance. Unfamiliar dyads and dyads interacting in more collaborative tasks were relatively warmer, more submissive, and more complementary on warmth but less complementary on dominance. These findings speak to the utility of the CAID method for assessing interpersonal dynamics and provide norms for researchers who use the method for different types of samples and applications.
              Cover page: Properties of the Continuous Assessment of Interpersonal Dynamics Across Sex, Level of Familiarity, and Interpersonal Conflict
              • Article
              • Peer Reviewed
              UCLA Previously Published Works (2018)
              Microbial aromatic catabolism offers a promising approach to convert lignin, a vast source of renewable carbon, into useful products. Aryl-O-demethylation is an essential biochemical reaction to ultimately catabolize coniferyl and sinapyl lignin-derived aromatic compounds, and is often a key bottleneck for both native and engineered bioconversion pathways. Here, we report the comprehensive characterization of a promiscuous P450 aryl-O-demethylase, consisting of a cytochrome P450 protein from the family CYP255A (GcoA) and a three-domain reductase (GcoB) that together represent a new two-component P450 class. Though originally described as converting guaiacol to catechol, we show that this system efficiently demethylates both guaiacol and an unexpectedly wide variety of lignin-relevant monomers. Structural, biochemical, and computational studies of this novel two-component system elucidate the mechanism of its broad substrate specificity, presenting it as a new tool for a critical step in biological lignin conversion.
                Cover page: A promiscuous cytochrome P450 aromatic O-demethylase for lignin bioconversion
                • Article
                • Peer Reviewed
                UC San Francisco Previously Published Works (2014)
                Tourette syndrome (TS) is characterized by tics, sensorimotor gating deficiencies, and abnormalities of cortico-basal ganglia circuits. A mutation in histidine decarboxylase (Hdc), the key enzyme for the biosynthesis of histamine (HA), has been implicated as a rare genetic cause. Hdc knockout mice exhibited potentiated tic-like stereotypies, recapitulating core phenomenology of TS; these were mitigated by the dopamine (DA) D2 antagonist haloperidol, a proven pharmacotherapy, and by HA infusion into the brain. Prepulse inhibition was impaired in both mice and humans carrying Hdc mutations. HA infusion reduced striatal DA levels; in Hdc knockout mice, striatal DA was increased and the DA-regulated immediate early gene Fos was upregulated. DA D2/D3 receptor binding was altered both in mice and in humans carrying the Hdc mutation. These data confirm histidine decarboxylase deficiency as a rare cause of TS and identify HA-DA interactions in the basal ganglia as an important locus of pathology.
                  Cover page: Histidine Decarboxylase Deficiency Causes Tourette Syndrome: Parallel Findings in Humans and Mice
                  • Article
                  • Peer Reviewed
                  UCLA Previously Published Works (2019)
                  Microbial conversion of aromatic compounds is an emerging and promising strategy for valorization of the plant biopolymer lignin. A critical and often rate-limiting reaction in aromatic catabolism is O-aryl-demethylation of the abundant aromatic methoxy groups in lignin to form diols, which enables subsequent oxidative aromatic ring-opening. Recently, a cytochrome P450 system, GcoAB, was discovered to demethylate guaiacol (2-methoxyphenol), which can be produced from coniferyl alcohol-derived lignin, to form catechol. However, native GcoAB has minimal ability to demethylate syringol (2,6-dimethoxyphenol), the analogous compound that can be produced from sinapyl alcohol-derived lignin. Despite the abundance of sinapyl alcohol-based lignin in plants, no pathway for syringol catabolism has been reported to date. Here we used structure-guided protein engineering to enable microbial syringol utilization with GcoAB. Specifically, a phenylalanine residue (GcoA-F169) interferes with the binding of syringol in the active site, and on mutation to smaller amino acids, efficient syringol O-demethylation is achieved. Crystallography indicates that syringol adopts a productive binding pose in the variant, which molecular dynamics simulations trace to the elimination of steric clash between the highly flexible side chain of GcoA-F169 and the additional methoxy group of syringol. Finally, we demonstrate in vivo syringol turnover in Pseudomonas putida KT2440 with the GcoA-F169A variant. Taken together, our findings highlight the significant potential and plasticity of cytochrome P450 aromatic O-demethylases in the biological conversion of lignin-derived aromatic compounds.
                    Cover page: Enabling microbial syringol conversion through structure-guided protein engineering
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