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Open Access Publications from the University of California

Scholarly Works (23 results)

  • Article
  • Peer Reviewed
Journal of Transnational American Studies, Volume 13, Issue 2 (2022)

Aeriality has emerged as one of the most defining perceptual and cognitive practices of the 20th century. This shift in perspective has changed the way one looks at the Earth, races, and species and their relationships to one another and to the environment. In this essay, I discuss the use of what I have heuristically termed “aerial archives” in teaching about American-occupied Japan (1945–1952). The operational definition of this term refers to texts, literary or otherwise, that operate as archiving systems, representing and relating a shift in the aerial imagination, and the corollary shifting ground it caused in the global imagination.

    Cover page: United States Aerial Archives: Teaching and Theorizing Transnational American Studies in Japan
    • Thesis
    • Peer Reviewed
    UC Berkeley Electronic Theses and Dissertations (2014)

    While some microbial encounters can be pathogenic, most interactions between humans and microorganisms do not result in disease. Our gastrointestinal tract harbors approximately 100 trillion organisms, spanning about 1000 species that live in harmony with us. While we provide them with food and shelter, this complex intestinal bacterial community supplies essential nutrients, metabolizes indigestible compounds, protects us from pathogenic organisms and helps develop our immune system, thereby establishing a symbiotic relationship. Bacteroides are one of the most abundant bacterial genera living in the human gut and has long been a model system for studying the molecular mechanisms of commensal-host interactions. In the course of searching for surface structures that have immunomodulatory properties on the host, we serendipitously discovered a previously unknown surface protein BT1927 from Bacteroides that is capable of completely covering the surface of the bacteria by creating a tessellated surface layer. Interestingly, the formation of the entire proteinaceous capsule is controlled by inversion of a single promoter, making it phase-variable. Although only ~ 0.1% of the population produce this capsule in laboratory culture, analyzing the fecal metagenome sequence data from the Human Microbiome Project revealed that ~ 8% of the population produce a homologous capsule in humans, suggesting its significance in vivo. From a series of functional studies, we found that the BT1927-expressing subpopulation is profoundly resistant to complement-mediated killing, due in part to the BT1927-mediated blockade of C3b deposition. Our results show that the Bacteroides capsule is capable of a far greater degree of structural variation than previously known, perhaps to cope with the varying environmental conditions in the human intestine.

      Cover page: A Phase-Variable Surface Layer from the Human Gut Commensal Bacteroides
      • Article
      • Peer Reviewed
      UC Irvine Previously Published Works (1996)
      The very different anatomical designs of the adjacent circuitries of the cortico-hippocampal pathway, along with their somewhat different synaptic plasticity mechanisms, suggest a nearly serial pathway of distinct memory circuits each contributing its own specialized processing operation to overall hippocampal function. Modeling and formal theoretical analysis of the prominent anatomical design features of particular circuits (piriform/entorhinal cortex; hippocampal field CA3; hippocampal field CA1) are found to identify potential emergent function not readily arrived at in the absence of these formal models, and yet which once derived can be seen potentially to confer unique capabilities to an integrated hippocampal mechanism for processing memories during behavior.
        Cover page: Distinct memory circuits composing the hippocampal region
        • Article
        • Peer Reviewed
        UC Irvine Previously Published Works (2002)
        Long-term potentiation (LTP) was elicited by high frequency stimulation in hippocampal slices cultured on multi-electrode arrays. LTP lasting more than 1 h was recorded in 75% of slices, and a significant number of slices exhibited a non-decaying LTP that lasted more than 48 h. LTP induction was completely and reversibly blocked by an antagonist of the NMDA receptor, APV. Our results suggest the possibility of using chronic recording in hippocampal slices cultured on multi-electrode arrays to study the mechanisms underlying LTP maintenance and stabilization.
          Cover page: Long‐Term Recording of LTP in Cultured Hippocampal Slices
          • Article
          • Peer Reviewed
          UC San Francisco Previously Published Works (2015)
          © 2015 Taketani et al.The capsule from Bacteroides, a common gut symbiont, has long been a model system for studying the molecular mechanisms of host-symbiont interactions. The Bacteroides capsule is thought to consist of an array of phase-variable polysac
            • Article
            • Peer Reviewed
            UC San Francisco Previously Published Works (2023)

            Introduction

            Periodontitis-related oral microbial dysbiosis is thought to contribute to Alzheimer's disease (AD) neuroinflammation and brain amyloid production. Since probiotics can modulate periodontitis/oral dysbiosis, this study examined the effects of a probiotic/lantibiotic, nisin, in modulating brain pathology triggered by periodontitis.

            Methods

            A polymicrobial mouse model of periodontal disease was used to evaluate the effects of this disease on brain microbiome dysbiosis, neuroinflammation, Alzheimer's-related changes, and nisin's therapeutic potential in this context.

            Results

            16S sequencing and real-time PCR data revealed that Nisin treatment mitigated the changes in the brain microbiome composition, diversity, and community structure, and reduced the levels of periodontal pathogen DNA in the brain induced by periodontal disease. Nisin treatment significantly decreased the mRNA expression of pro-inflammatory cytokines (Interleukin-1β/IL-1 β, Interleukin 6/IL-6, and Tumor Necrosis Factor α/TNF-α) in the brain that were elevated by periodontal infection. In addition, the concentrations of amyloid-β 42 (Aβ42), total Tau, and Tau (pS199) (445.69 ± 120.03, 1420.85 ± 331.40, 137.20 ± 36.01) were significantly higher in the infection group compared to the control group (193.01 ± 31.82, 384.27 ± 363.93, 6.09 ± 10.85), respectively. Nisin treatment markedly reduced the Aβ42 (261.80 ± 52.50), total Tau (865.37 ± 304.93), and phosphorylated Tau (82.53 ± 15.77) deposition in the brain of the infection group.

            Discussion

            Nisin abrogation of brain microbiome dysbiosis induces beneficial effects on AD-like pathogenic changes and neuroinflammation, and thereby may serve as a potential therapeutic for periodontal-dysbiosis-related AD.
              Cover page: Nisin a probiotic bacteriocin mitigates brain microbiome dysbiosis and Alzheimer’s disease-like neuroinflammation triggered by periodontal disease
              • Article
              • Peer Reviewed
              UCLA Previously Published Works (2021)
              With 1.5-2.0 million new cases annually worldwide, corneal injury represents a common cause of vision loss, often from irreversible scarring due to surface corneal defects. In this study, we assessed the use of hepatocyte growth factor (HGF) loaded into an in situ photopolymerizable transparent gelatin-based hydrogel for the management of corneal defects. In vitro release kinetics showed that, in regard to the total amount of HGF released over a month, 55 ± 11% was released during the first 24 h, followed by a slow release profile for up to one month. The effect of HGF was assessed using an ex vivo model of pig corneal defect. After three days of organ culture, epithelial defects were found to be completely healed for 89% of the corneas treated with HGF, compared to only 11% of the corneas that had fully re-epithelialized when treated with the hydrogel without HGF. The thickness of the epithelial layer was found to be significantly higher for the HGF-treated group compared to the group treated with hydrogel without HGF (p = 0.0012). Finally, histological and immunostaining assessments demonstrated a better stratification and adhesion of the epithelial layer in the presence of HGF. These results suggest that the HGF-loaded hydrogel system represents a promising solution for the treatment of persistent corneal defects at risk of scarring.
                Cover page: Growth factor-eluting hydrogels for management of corneal defects
                • Article
                • Peer Reviewed
                UC San Francisco Previously Published Works (2012)
                Hyperphosphatemia causes endothelial dysfunction as well as vascular calcification. Management of serum phosphate level by dietary phosphate restriction or phosphate binders is considered to be beneficial to prevent chronic kidney disease patients from car
                  • Article
                  • Peer Reviewed
                  UCLA Previously Published Works (2022)
                  Full-thickness wounds to the eye can lead to serious vision impairment. Current standards of care (from suturing to tissue transplantation) usually require highly skilled surgeons and use of an operating theater. In this study, we report the synthesis, optimization, and in vitro and ex vivo testing of photocrosslinkable hydrogel-based adhesive patches that can easily be applied to globe injuries or corneal incisions. According to the type and concentration of polymers used in the adhesive formulations, we were able to finely tune the physical properties of the bioadhesive including viscosity, elastic modulus, extensibility, ultimate tensile strength, adhesion, transparency, water content, degradation time, and swellability. Our in vitro studies showed no sign of cytotoxicity of the hydrogels. Moreover, the hydrogel patches showed higher adhesion on freshly explanted pig eyeballs compared to a marketed ocular sealant. Finally, ex vivo feasibility studies showed that the hydrogel patches could seal complex open-globe injuries such as large incision, cruciform injury, and injury associated with tissue loss. These results suggest that our photocrosslinkable hydrogel patch could represent a promising solution for the sealing of open-globe injuries or surgical incisions. STATEMENT OF SIGNIFICANCE: Current management of severe ocular injuries require advanced surgical skills and access to an operating theater. To address the need for emergent management of wounds that cannot be handled in the operating room, surgical adhesives have gained popularity, but none of the currently available adhesives have optimal bioavailability, adhesive or mechanical properties. This study describes the development, optimization and testing of a light-sensitive adhesive patch that can easily be applied to the eye. After solidification using visible light, the patch shows no toxicity and is more adherent to the tissue than a marketed sealant. Thus this technology could represent a promising solution to stabilize ocular injuries in emergency settings before definitive surgical repair.
                    Cover page: Development and characterization of a hydrogel-based adhesive patch for sealing open-globe injuries
                    • Article
                    • Peer Reviewed
                    UC San Francisco Previously Published Works (2014)
                    Several recent studies describe the influence of the gut microbiota on host brain and behavior. However, the mechanisms responsible for microbiota-nervous system interactions are largely unknown. Using a combination of genetics, biochemistry, and crystallography, we identify and characterize two phylogenetically distinct enzymes found in the human microbiome that decarboxylate tryptophan to form the β-arylamine neurotransmitter tryptamine. Although this enzymatic activity is exceedingly rare among bacteria more broadly, analysis of the Human Microbiome Project data demonstrate that at least 10% of the human population harbors at least one bacterium encoding a tryptophan decarboxylase in their gut community. Our results uncover a previously unrecognized enzymatic activity that can give rise to host-modulatory compounds and suggests a potential direct mechanism by which gut microbiota can influence host physiology, including behavior.
                      Cover page: Discovery and Characterization of Gut Microbiota Decarboxylases that Can Produce the Neurotransmitter Tryptamine
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