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Open Access Publications from the University of California

Scholarly Works (52 results)

  • Article
  • Peer Reviewed
UC Irvine Previously Published Works (2012)
    Cover page: Neuroendocrine Mechanisms of Acupuncture in the Treatment of Hypertension
    • Thesis
    • Peer Reviewed
    UC San Diego Electronic Theses and Dissertations (2022)

    Animals in nature move through the rhythmic oscillation of their appendages and bodies. Similar oscillatory motion is a hallmark of bioinspired robots, which seek to embed biological principles into the design, sensing, and control of robots. While there is a robust theory of nonlinear oscillatory systems, there still exist fundamental gaps in knowledge when considering robotic locomotion. For example, ground-based robots make intermittent contact with the ground to propel themselves forward or to turn, and such ``making and breaking'' of contact between the oscillatory actuation source and the environment can lead to novel locomotion challenges. Additionally, when multiple robots are moving together the coordination of rhythmic gaits (such as through synchronization) may lead to beneficial group movement. However, the methods to design such synchronized locomotion are not altogether straightforward especially when considering potential communication limitations between robots. This dissertation addresses specific problems in oscillatory locomotion of bioinspired robots. In the first study the author developed a inch-worm inspired robot that can push and pull against the ground with simple ``feet'' to propel itself. The author studied how basic feedforward oscillatory actuation of the ``feet'' leads to non-trivial locomotion dynamics through foot slipping and stochastic foot-ground contact mechanics. In follow up work the author demonstrated enhanced capabilities of this robot such as turning, that was achieved through incorporation of soft materials in the design process. In the third study the author studied the collective behavior of simple three-link ``swimming'' robots that are controlled through feedforward oscillatory actuation. Oscillatory phase differences between neighboring robots lead to intermittent collisions that drive the group into a stable spatial configuration by lateral and longitudinal movement. We derive conditions for group spacing and density based on phase variation, examine the effective interaction potential between neighboring robots, and identify a compatibility condition for robots to safely swim in close proximity without collisions. In the last study the author enables the oscillatory motion of robot's in a collective to be generated through nonlinear, limit-cycle dynamics. The author finds that intermittent contact between robots leads to overall group synchronization of oscillatory swimming gaits which reduces contact forces between robots and enables high density configurations. A phase oscillator model of this process is developed and the author derives the theoretical conditions for group synchronization, observing good agreement between experiments and the theoretical model. This work enables the author to demonstrate in experiment the swimming synchronization of four three-link robots that do not communicate with each other, but instead leverage the nonlinear dynamics of the nonlinear oscillator control system. Ultimately, the work the author presents in this thesis leads to new understanding of how oscillatory motion is influenced by intermittent, nonlinear, interactions with the environment and between robots.

      Cover page: Design of oscillatory movement for ground-based locomotion and synchronized movement in bioinspired robotics
      • Article
      • Peer Reviewed
      UC Irvine Previously Published Works (2024)
      The relationship between heart failure and diabetes is intricate and bidirectional. Individuals with diabetes face an elevated risk of developing heart failure due to factors like insulin resistance, chronic inflammation, and metabolic irregularities. Elevated blood sugar levels can harm blood vessels and nerves, culminating in the buildup of fatty deposits in arteries, atherosclerosis, and hypertension, which significantly contribute to heart failure. Furthermore, diabetes can adversely impact the structure and function of the heart muscle, impairing its pumping capacity. Conversely, heart failure can also contribute to the onset of diabetes by disrupting the bodys metabolic processes and amplifying insulin resistance. The complex interaction between these conditions mandates a comprehensive approach to managing individuals with both diabetes and heart failure, underscoring the importance of addressing both aspects for enhanced patient outcomes. Although existing pharmacological treatments are limited and frequently associated with undesirable side effects, acupuncture has established itself as a traditional practice with a legacy. It remains a supplementary option for treating cardiovascular diseases. Heart failure and diabetes are both heavily associated with chronic upregulation of the sympathetic nervous system, which has been identified as a pivotal factor in the progression of disease. Mechanistic interplays such as the attenuation of central nitric oxide signaling may interfere with the production or availability of nitric oxide in key areas of the central nervous system, including the brainstem and hypothalamus. This review will delve into the current understanding of acupuncture on the autonomic nervous system and offer insights into its potential role in the future treatment landscape for diabetes and heart failure.
        Cover page: Integrative care: acupuncture based neuromodulation therapy for diabetes and heart failure.
        • Article
        • Peer Reviewed
        UC Irvine Previously Published Works (2019)
          Cover page: 311 Global Longitudinal Strain and Ejection Fraction in ESRD vs. Non-ESRD Patients
          • Article
          • Peer Reviewed
          UC Irvine Previously Published Works (2019)
            Cover page: 312 Global Longitudinal Strain and Left Ventricular Mass in ESRD and Non-ESRD Patients
            • Article
            Electric Grid (2008)
            To investigate models, sensing systems and other means for detecting, in advance of failure, the degradation of the concentric neutral conductors of underground power distribution cables.
              Cover page: Feasibility Assessment and Research Results Report
              • Article
              • Peer Reviewed
              UC San Francisco Previously Published Works (2022)
              Hypothalamic orexin (hypocretin) neurons play crucial roles in arousal control. Their involvement in anesthesia and analgesia remains to be better understood. In order to enhance our view on the neuroanatomy, we systematically mapped the projections of orexin neurons with confocal microscope and light sheet microscope. We specifically expressed optogenetic opsins tagged with fluorescence markers in orexin neurons through adeno-associated viral infection in the mouse brain. The imaging results revealed fine details and novel features of the orexin projections throughout the brain, particularly related to the nuclei regulating arousal and pain. We then optogenetically activated orexin neurons in the lateral hypothalamus to study the effects on anesthesia-related behaviors. cFos staining showed that optogenetic stimulation can activate orexin neurons in the ChR2-mCherry group, but not the control mCherry group (62.86 ± 3.923% vs. 7.9 ± 2.072%; P < 0.0001). In behavior assays, optogenetic stimulation in the ChR2-mCherry group consistently elicited robust arousal from light isoflurane anesthesia (9.429 ± 3.804 s vs. 238.2 ± 17.42 s; P < 0.0001), shortened the emergence time after deep isoflurane anesthesia (109.5 ± 13.59 s vs. 213.8 ± 21.77 s; P = 0.0023), and increased the paw withdrawal latency in a hotplate test (11.45 ± 1.185 s vs. 8.767 ± 0.7775; P = 0.0317). The structural details of orexin fibers established the neuroanatomic basis for studying the role of orexin in anesthesia and analgesia.
                Cover page: Neuroanatomical Basis for the Orexinergic Modulation of Anesthesia Arousal and Pain Control
                • Article
                • Peer Reviewed
                UC San Francisco Previously Published Works (2018)
                Orexin (also known as hypocretin) neurons in the hypothalamus play an essential role in sleep-wake control, feeding, reward, and energy homeostasis. The likelihood of anesthesia and sleep sharing common pathways notwithstanding, it is important to understand the processes underlying emergence from anesthesia. In this study, we investigated the role of the orexin system in anesthesia emergence, by specifically activating orexin neurons utilizing the designer receptors exclusively activated by designer drugs (DREADD) chemogenetic approach. With injection of adeno-associated virus into the orexin-Cre transgenic mouse brain, we expressed the DREADD receptor hM3Dq specifically in orexin neurons and applied the hM3Dq ligand clozapine to activate orexin neurons. We monitored orexin neuronal activities by c-Fos staining and whole-cell patch-clamp recording and examined the consequence of orexin neuronal activation via EEG recording. Our results revealed that the orexin-DREADD mice with activated orexin neurons emerged from anesthesia with significantly shorter latency than the control mice. As an indication of reduced pain sensitivity, these orexin-DREADD mice took longer to respond to the 55 °C thermal stimuli in the hot plate test and exhibited significantly less frequent licking of the formalin-injected paw in the formalin test. Our study suggests that approaches to activate the orexin system can be beneficial in postoperative recovery.
                  Cover page: Activation of orexin system facilitates anesthesia emergence and pain control
                  • Article
                  • Peer Reviewed
                  UC San Diego Previously Published Works (2014)
                  Four new briarane diterpenoids, junceellolides M-P (1-4), were isolated together with seven known analogs (5-11) from the South China Sea gorgonian, Junceella gemmacea. The structures of these compounds were elucidated by detailed spectroscopic analysis and comparison with the reported data. The absolute configuration of compounds 1-3 were determined based on an ECD experiment, while the absolute configuration of compound 4 was genetically determined. All the compounds were isolated for the first time from J. gemmacea. These compounds showed no growth inhibitory activity against A549, MG63 and SMMC-7721 cell lines in an in vitro bioassay.
                    Cover page: Briarane Diterpenes from the South China Sea Gorgonian Coral, Junceella gemmacea
                    • Article
                    • Peer Reviewed
                    UCLA Previously Published Works (2013)

                    Background

                    Radiofrequency ablation for ventricular tachycardia is an established therapy. Use of chemical agents for scar homogenization represents an alternative approach. The purpose of this study was to characterize the efficacy of collagenase (CLG) application on epicardial ventricular scar homogenization.

                    Methods and results

                    Myocardial infarcts were created in Yorkshire pigs (n=6) by intracoronary microsphere injection. After 46.6±4.3 days, CLG type 2, type 4, and purified CLG were applied in vitro (n=1) to myocardial tissue blocks containing normal myocardium, border zone, and dense scar. Histopathologic studies were performed to identify the optimal CLG subtype. In vivo high-density electroanatomic mapping of the epicardium was also performed, and border zone and dense scar surface area and late potentials were quantified before and after CLG-4 application (n=5). Of the CLG subtypes tested in vitro, CLG-4 provided the best scar modification and least damage to normal myocardium. During in vivo testing, CLG-4 application decreased border zone area (21.3±14.3 to 17.1±11.1 mm(2), P=0.043) and increased dense scar area (9.1±10.3 to 22.0±20.6 mm(2), P=0.043). The total scar area before and after CLG application was 30.4±23.4 and 39.2±29.5 mm(2), respectively (P=0.08). Late potentials were reduced by CLG-4 application (28.8±21.8 to 13.8±13.1, P=0.043). During CLG-4 application (50.0±15.5 minutes), systolic blood pressure and heart rate were not significantly changed (68.0±7.7 versus 61.8±5.3 mmHg, P=0.08; 77.4±7.3 versus 78.8±6.0 beats per minute, P=0.50, respectively).

                    Conclusions

                    Ventricular epicardial scar homogenization by CLG-4 application is feasible and effective. This represents the first report on bioenzymatic ablation of arrhythmogenic tissue as an alternative strategy for lesion formation.
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