The Role of Selenocysteine Lyase in Pancreatic Islet Physiology and its Sex-Specific Regulation of Energy Metabolism.

Ph.D. Thesis. University of Hawaiʻi at Mānoa 2017

Frequency Domain Simulations of Charge-Density-Wave Strains: Comparison with Electro-Optic Measurements

We have studied changes in charge-density-wave strain under application of square-wave currents of variable amplitude and frequency by numerically solving the phase-slip augmented diffusion model introduced by Adelman et al (Phys. Rev. B 53, 1833 (1996)). The frequency dependence of the strain, at each position and amplitude, was fit to a modified harmonic oscillator expression, and the position and current dependence of the fitting parameters determined. In particular, the delay time (1/resonant frequency) vanishes adjacent to the contact and grows with distance from the contact, and both the delay time and relaxation time decrease rapidly with increasing current (and phase-slip rate), as experimentally observed in the electro-optic response of blue bronze. We have also found that pinning the phase at the contacts causes more rapid changes in strain between the contacts than allowing the phase to flow outside the contacts.Comment: 12 pages, 4 figures, submitted to Phys. Rev.

Measurement of the Intrinsic Radiopurity of Cs-137/U-235/U-238/Th-232 in CsI(Tl) Crystal Scintillators

The inorganic crystal scintillator CsI(Tl) has been used for low energy neutrino and Dark Matter experiments, where the intrinsic radiopurity is an issue of major importance. Low-background data were taken with a CsI(Tl) crystal array at the Kuo-Sheng Reactor Neutrino Laboratory. The pulse shape discrimination capabilities of the crystal, as well as the temporal and spatial correlations of the events, provide powerful means of measuring the intrinsic radiopurity of Cs-137 as well as the U-235, U-238 and Th-232 series. The event selection algorithms are described, with which the decay half-lives of Po-218, Po-214, Rn-220, Po-216 and Po-212 were derived. The measurements of the contamination levels, their concentration gradients with the crystal growth axis, and the uniformity among different crystal samples, are reported. The radiopurity in the U-238 and Th-232 series are comparable to those of the best reported in other crystal scintillators. Significant improvements in measurement sensitivities were achieved, similar to those from dedicated massive liquid scintillator detector. This analysis also provides in situ measurements of the detector performance parameters, such as spatial resolution, quenching factors, and data acquisition dead time.Comment: 28 pages, 12 figure

Lactobacillus reuteri inhibition of Enteropathogenic Escherichia coli adherence to human intestinal epithelium

Enteropathogenic Escherichia coli (EPEC) is a major cause of diarrheal infant death in developing countries, and probiotic bacteria have been shown to provide health benefits in gastrointestinal infections. In this study, we have investigated the influence of the gut symbiont Lactobacillus reuteri on EPEC adherence to the human intestinal epithelium. Different host cell model systems including non-mucus-producing HT-29 and mucus-producing LS174T intestinal epithelial cell lines as well as human small intestinal biopsies were used. Adherence of L. reuteri to HT-29 cells was strain-specific, and the mucus-binding proteins CmbA and MUB increased binding to both HT-29 and LS174T cells. L. reuteri ATCC PTA 6475 and ATCC 53608 significantly inhibited EPEC binding to HT-29 but not LS174T cells. While pre-incubation of LS174T cells with ATCC PTA 6475 did not affect EPEC attaching/effacing (A/E) lesion formation, it increased the size of EPEC microcolonies. ATCC PTA 6475 and ATCC 53608 binding to the mucus layer resulted in decreased EPEC adherence to small intestinal biopsy epithelium. Our findings show that L. reuteri reduction of EPEC adhesion is strain-specific and has the potential to target either the epithelium or the mucus layer, providing further rationale for the selection of probiotic strains

Effects of Stellate Ganglion Cryoablation on Subcutaneous Nerve Activity and Atrial Tachyarrhythmias in a Canine Model of Pacing-Induced Heart Failure

OBJECTIVES: This study aimed to test the hypothesis that subcutaneous nerve activity (SCNA) can adequately estimate the cardiac sympathetic tone and the effects of cryoablation of the stellate ganglion in dogs with pacing-induced heart failure (HF). BACKGROUND: Recording of SCNA is a new method to estimate sympathetic tone in dogs. HF is known to increase sympathetic tone and atrial arrhythmias. METHODS: Twelve dogs with pacing-induced HF were studied using implanted radiotransmitters to record the stellate ganglia nerve activity (SGNA), vagal nerve activity, and SCNA. Of these, 6 dogs (ablation group) underwent bilateral stellate ganglia cryoablation before the rapid ventricular pacing; the remaining 6 dogs (control group) had rapid ventricular pacing only. In both groups, SCNA was compared with SGNA and the occurrence of arrhythmias. RESULTS: SCNA invariably increased before the 360 identified atrial tachyarrhythmia episodes in the 6 control dogs before and after HF induction. SCNA and SGNA correlated in all dogs with an average correlation coefficient of 0.64 (95% confidence interval: 0.58 to 0.70). Cryoablation of bilateral stellate ganglia significantly reduced SCNA from 0.34 ± 0.033 μV to 0.25 ± 0.028 μV (p = 0.03) and eliminated all atrial tachyarrhythmias. CONCLUSIONS: SCNA can be used to estimate cardiac sympathetic tone in dogs with pacing-induced HF. Cryoablation of the stellate ganglia reduced SCNA and arrhythmia vulnerability

Charge- and parity-projected Hartree-Fock method for the strong tensor correlation and its application to the alpha particle

We propose a new mean-field-type framework which can treat the strong correlation induced by the tensor force. To treat the tensor correlation we break the charge and parity symmetries of a single-particle state and restore these symmetries of the total system by the projection method. We perform the charge and parity projections before variation and obtain a Hartree-Fock-like equation, which is solved self-consistently. We apply the Hartree-Fock-like equation to the alpha particle and find that by breaking the parity and charge symmetries, the correlation induced by the tensor force is obtained in the projected mean-field framework. We emphasize that the projection before the variation is important to pick up the tensor correlation in the present framework.Comment: 21 pages, 2 figure

Simultaneous acquisition of cerebral blood volume-, blood flow-, and blood oxygenation-weighted MRI signals at ultra-high magnetic field

Purpose Yang et al. proposed an MRI technique for the simultaneous acquisition of cerebral blood volume (CBV), cerebral blood flow (CBF), and blood oxygenation level-dependent (BOLD)-weighted MRI signals (9). The purpose of this study was to develop modified version of the Yang sequence, which utilizes the advantages of 7 Tesla, leading to a robust and reliable MRI sequence. MethodsThe inversion recovery-based MR pulse sequence introduced here involves slice-saturation slab-inversion vascular space occupancy (SI-SS-VASO) MRI, double echo planar imaging readouts for arterial spin labeling, and VASO in order to correct for BOLD contamination, and a separate BOLD acquisition to minimize inversion effects on the BOLD signal. A standard visual stimulus block design was used to evaluate the spatial and temporal characteristics of CBV-, CBF-, and BOLD-weighted images. ResultsThe high signal-to-noise ratio and spatial resolution of this method leads to robust activation maps. This technique enables the investigation of the differential spatial specificity and temporal characteristics of the different modalities. ConclusionThe pulse sequence could be a powerful tool for studies of neurovascular coupling, hemodynamic response, or calibrated BOLD. Magn Reson Med 74:513-517, 2015

Special considerations for therapeutic choice of non-vitamin K antagonist oral anticoagulants for Japanese patients with nonvalvular atrial fibrillation.

Nonvalvular atrial fibrillation (AF) is a risk factor for stroke in elderly patients. Although warfarin has been used to prevent AF-associated stroke for more than 50 years, non-vitamin K antagonist oral anticoagulants (NOACs) including dabigatran, rivaroxaban, apixaban, and edoxaban recently have been developed to overcome the disadvantages of warfarin. Based on the results of NOAC clinical trials, Savelieva and Camm made recommendations regarding selection of NOACs in patients with nonvalvular AF. Recent accumulating evidence indicates that NOACs work differently in Asian and non-Asian individuals. In this review, we discuss the results of the large, randomized, phase 3 international clinical trials on NOACs, the subanalyses of Asians, and a Japanese phase 3 clinical trial of rivaroxaban to discriminate Japanese patient-specific characteristics with regard to their responses to NOACs and make recommendations. Our analysis revealed that rivaroxaban decreased the incidence of gastrointestinal (GI) bleeding compared with warfarin in Japanese patients. The efficacy results showed that rivaroxaban significantly decreased the incidence of ischemic stroke (hazard ratio: 0.40, 95% confidence interval: 0.17-0.96) compared with warfarin. The lower incidence of GI bleeding and ischemic stroke may be specific to Japanese patients. Based on the present and previous results, the following recommendations regarding the selection of NOACs are added in the Camm chart for Japanese patients: edoxaban for patients with a high risk of bleeding and those with a previous stroke; and rivaroxaban for patients with a high risk of ischemic stroke and a low bleeding risk, and those with previous GI bleeding