261 results on '"John H. Miller"'
Search Results
2. BaPreS: a software tool for predicting bacteriocins using an optimal set of features
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Suraiya Akhter and John H. Miller
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Antibiotic resistance ,Bacteriocin prediction ,Feature selection ,Machine learning ,Deep learning ,Sequence matching ,Computer applications to medicine. Medical informatics ,R858-859.7 ,Biology (General) ,QH301-705.5 - Abstract
Abstract Background Antibiotic resistance is a major public health concern around the globe. As a result, researchers always look for new compounds to develop new antibiotic drugs for combating antibiotic-resistant bacteria. Bacteriocin becomes a promising antimicrobial agent to fight against antibiotic resistance, due to cases of both broad and narrow killing spectra. Sequence matching methods are widely used to identify bacteriocins by comparing them with the known bacteriocin sequences; however, these methods often fail to detect new bacteriocin sequences due to their high diversity. The ability to use a machine learning approach can help find new highly dissimilar bacteriocins for developing highly effective antibiotic drugs. The aim of this work is to develop a machine learning-based software tool called BaPreS (Bacteriocin Prediction Software) using an optimal set of features for detecting bacteriocin protein sequences with high accuracy. We extracted potential features from known bacteriocin and non-bacteriocin sequences by considering the physicochemical and structural properties of the protein sequences. Then we reduced the feature set using statistical justifications and recursive feature elimination technique. Finally, we built support vector machine (SVM) and random forest (RF) models using the selected features and utilized the best machine learning model to implement the software tool. Results We applied BaPreS to an established dataset and evaluated its prediction performance. Acquired results show that the software tool can achieve a prediction accuracy of 95.54% for testing protein sequences. This tool allows users to add new bacteriocin or non-bacteriocin sequences in the training dataset to further enhance the predictive power of the tool. We compared the prediction performance of the BaPreS with a popular sequence matching-based tool and a deep learning-based method, and our software tool outperformed both. Conclusions BaPreS is a bacteriocin prediction tool that can be used to discover new highly dissimilar bacteriocins for developing highly effective antibiotic drugs. This software tool can be used with Windows, Linux and macOS operating systems. The open-source software package and its user manual are available at https://github.com/suraiya14/BaPreS .
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- 2023
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3. BPAGS: a web application for bacteriocin prediction via feature evaluation using alternating decision tree, genetic algorithm, and linear support vector classifier
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Suraiya Akhter and John H. Miller
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antimicrobial resistance ,antimicrobial peptides ,bacteriocin prediction ,drug discovery ,feature selection ,machine learning ,Computer applications to medicine. Medical informatics ,R858-859.7 - Abstract
The use of bacteriocins has emerged as a propitious strategy in the development of new drugs to combat antibiotic resistance, given their ability to kill bacteria with both broad and narrow natural spectra. Hence, a compelling requirement arises for a precise and efficient computational model that can accurately predict novel bacteriocins. Machine learning’s ability to learn patterns and features from bacteriocin sequences that are difficult to capture using sequence matching-based methods makes it a potentially superior choice for accurate prediction. A web application for predicting bacteriocin was created in this study, utilizing a machine learning approach. The feature sets employed in the application were chosen using alternating decision tree (ADTree), genetic algorithm (GA), and linear support vector classifier (linear SVC)-based feature evaluation methods. Initially, potential features were extracted from the physicochemical, structural, and sequence-profile attributes of both bacteriocin and non-bacteriocin protein sequences. We assessed the candidate features first using the Pearson correlation coefficient, followed by separate evaluations with ADTree, GA, and linear SVC to eliminate unnecessary features. Finally, we constructed random forest (RF), support vector machine (SVM), decision tree (DT), logistic regression (LR), k-nearest neighbors (KNN), and Gaussian naïve Bayes (GNB) models using reduced feature sets. We obtained the overall top performing model using SVM with ADTree-reduced features, achieving an accuracy of 99.11% and an AUC value of 0.9984 on the testing dataset. We also assessed the predictive capabilities of our best-performing models for each reduced feature set relative to our previously developed software solution, a sequence alignment-based tool, and a deep-learning approach. A web application, titled BPAGS (Bacteriocin Prediction based on ADTree, GA, and linear SVC), was developed to incorporate the predictive models built using ADTree, GA, and linear SVC-based feature sets. Currently, the web-based tool provides classification results with associated probability values and has options to add new samples in the training data to improve the predictive efficacy. BPAGS is freely accessible at https://shiny.tricities.wsu.edu/bacteriocin-prediction/.
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- 2024
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4. Deep ancestry of collapsing networks of nomadic hunter–gatherers in Borneo
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J. Stephen Lansing, Guy S. Jacobs, Sean S. Downey, Peter K. Norquest, Murray P. Cox, Steven L. Kuhn, John H. Miller, Safarina G. Malik, Herawati Sudoyo, and Pradiptajati Kusuma
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Hunter–gatherers ,prosocial behaviour ,Borneo ,Austronesia ,song language ,Human evolution ,GN281-289 ,Evolution ,QH359-425 - Abstract
Theories of early cooperation in human society often draw from a small sample of ethnographic studies of surviving populations of hunter–gatherers, most of which are now sedentary. Borneo hunter–gatherers (Punan, Penan) have seldom figured in comparative research because of a decades-old controversy about whether they are the descendants of farmers who adopted a hunting and gathering way of life. In 2018 we began an ethnographic study of a group of still-nomadic hunter–gatherers who call themselves Punan Batu (Cave Punan). Our genetic analysis clearly indicates that they are very unlikely to be the descendants of neighbouring agriculturalists. They also preserve a song language that is unrelated to other languages of Borneo. Dispersed travelling groups of Punan Batu with fluid membership use message sticks to stay in contact, co-operate and share resources as they journey between rock shelters and forest camps. Message sticks were once widespread among nomadic Punan in Borneo, but have largely disappeared in sedentary Punan villages. Thus the small community of Punan Batu offers a rare glimpse of a hunting and gathering way of life that was once widespread in the forests of Borneo, where prosocial behaviour extended beyond the face-to-face community, facilitating successful collective adaptation to the diverse resources of Borneo's forests.
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- 2022
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5. Searches for Extremely Metal-poor Galaxies Using Arecibo Legacy Fast ALFA–Selected Dwarf Galaxies
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John H. Miller Jr., John J. Salzer, Steven Janowiecki, Martha P. Haynes, and Alec S. Hirschauer
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Dwarf irregular galaxies ,Metallicity ,Galaxy spectroscopy ,Galaxy chemical evolution ,Star forming regions ,Galaxy abundances ,Astrophysics ,QB460-466 - Abstract
We present a study of nearby dwarf galaxies selected from the Arecibo Legacy Fast ALFA (ALFALFA) blind H i survey. A primary goal of the project was to utilize a nonstandard selection method with the hope of detecting previously unrecognized extremely metal-poor (XMP) galaxies. The study was motivated by the recent discovery of two XMP galaxies, Leo P and Leoncino, which were both originally found via the ALFALFA survey. We have obtained narrowband H α images for 42 dwarf systems, many of which are located in the Local Void in front of the Pisces–Perseus Supercluster. Spectra for 11 of the best candidates resulted in the determination of metal abundances for 10 of the systems. None were found to be extremely metal-poor, although one system (AGC 123350) was found to have an oxygen abundance of log(O/H)+12 = 7.46, or ∼6% solar. One of the galaxies in our sample exhibits a high oxygen abundance for its luminosity, suggesting the possibility that it may have a tidal origin.
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- 2023
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6. Non-Targeted Analysis Using Gas Chromatography-Mass Spectrometry for Evaluation of Chemical Composition of E-Vapor Products
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Niti H. Shah, Michael R. Noe, Kimberly A. Agnew-Heard, Yezdi B. Pithawalla, William P. Gardner, Saibal Chakraborty, Nicholas McCutcheon, Hannah Grisevich, Thomas J. Hurst, Michael J. Morton, Matt S. Melvin, and John H. Miller IV
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non-targeted analysis ,electronic vapor products ,ENDS ,aerosol ,e-liquids ,semi-quantitative analysis ,Chemistry ,QD1-999 - Abstract
The Premarket Tobacco Product Applications (PMTA) guidance issued by the Food and Drug Administration for electronic nicotine delivery systems (ENDSs) recommends that in addition to reporting harmful and potentially harmful constituents (HPHCs), manufacturers should evaluate these products for other chemicals that could form during use and over time. Although e-vapor product aerosols are considerably less complex than mainstream smoke from cigarettes and heated tobacco product (HTP) aerosols, there are challenges with performing a comprehensive chemical characterization. Some of these challenges include the complexity of the e-liquid chemical compositions, the variety of flavors used, and the aerosol collection efficiency of volatile and semi-volatile compounds generated from aerosols. In this study, a non-targeted analysis method was developed using gas chromatography-mass spectrometry (GC-MS) that allows evaluation of volatile and semi-volatile compounds in e-liquids and aerosols of e-vapor products. The method employed an automated data analysis workflow using Agilent MassHunter Unknowns Analysis software for mass spectral deconvolution, peak detection, and library searching and reporting. The automated process ensured data integrity and consistency of compound identification with >99% of known compounds being identified using an in-house custom mass spectral library. The custom library was created to aid in compound identifications and includes over 1,100 unique mass spectral entries, of which 600 have been confirmed from reference standard comparisons. The method validation included accuracy, precision, repeatability, limit of detection (LOD), and selectivity. The validation also demonstrated that this semi-quantitative method provides estimated concentrations with an accuracy ranging between 0.5- and 2.0-fold as compared to the actual values. The LOD threshold of 0.7 ppm was established based on instrument sensitivity and accuracy of the compounds identified. To demonstrate the application of this method, we share results from the comprehensive chemical profile of e-liquids and aerosols collected from a marketed e-vapor product. Applying the data processing workflow developed here, 46 compounds were detected in the e-liquid formulation and 55 compounds in the aerosol sample. More than 50% of compounds reported have been confirmed with reference standards. The profiling approach described in this publication is applicable to evaluating volatile and semi-volatile compounds in e-vapor products.
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- 2021
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7. Possible transport evidence for three-dimensional topological superconductivity in doped β-PdBi2
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Ayo Kolapo, Tingxin Li, Pavan Hosur, and John H. Miller
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Medicine ,Science - Abstract
Abstract Interest in topological states of matter burgeoned over a decade ago with the theoretical prediction and experimental detection of topological insulators, especially in bulk three-dimensional insulators that can be tuned out of it by doping. Their superconducting counterpart, the fully-gapped three-dimensional time-reversal-invariant topological superconductors, have evaded discovery in bulk intrinsic superconductors so far. The recently discovered topological metal β-PdBi2 is a unique candidate for tunable bulk topological superconductivity because of its intrinsic superconductivity and spin-orbit-coupling. In this work, we provide experimental transport signatures consistent with fully-gapped 3D time-reversal-invariant topological superconductivity in K-doped β-PdBi2. In particular, we find signatures of odd-parity bulk superconductivity via upper-critical field and magnetization measurements— odd-parity pairing can be argued, given the band structure of β-PdBi2, to result in 3D topological superconductivity. In addition, Andreev spectroscopy reveals surface states protected by time-reversal symmetry which might be possible evidence of Majorana surface states (Majorana cone). Moreover, we find that the undoped bulk system is a trivial superconductor. Thus, we discover β-PdBi2 as a unique bulk material that, on doping, can potentially undergo an unprecedented topological quantum phase transition in the superconducting state.
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- 2019
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8. Paradoxes in leaky microbial trade
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Yoav Kallus, John H. Miller, and Eric Libby
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Science - Abstract
Microbes live in communities and exchange metabolites, but the resulting dynamics are poorly understood. Here, the authors study the interplay between metabolite production strategies and population dynamics, and find that complex and unexpected dynamics emerge even in simple microbial economies.
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- 2017
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9. Dissolution Testing of Nicotine Release from OTDN Pouches: Product Characterization and Product-to-Product Comparison
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Fadi Aldeek, Nicholas McCutcheon, Cameron Smith, John H. Miller, and Timothy L. Danielson
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on!® nicotine pouches ,nicotine ,dissolution ,release profile ,validation ,product assessment ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
In recent years, oral tobacco-derived nicotine (OTDN) pouches have emerged as a new oral tobacco product category. They are available in a variety of flavors and do not contain cut or ground tobacco leaf. The on!® nicotine pouches fall within this category of OTDN products and are currently marketed in seven (7) flavors with five (5) different nicotine levels. Evaluation of the nicotine release from these products is valuable for product assessment and product-to-product comparisons. In this work, we characterized the in vitro release profiles of nicotine from the 35 varieties of on!® nicotine pouches using a fit-for-purpose dissolution method, employing the U.S. Pharmacopeia flow-through cell dissolution apparatus 4 (USP-4). The nicotine release profiles were compared using the FDA’s Guidance for Industry: Dissolution Testing of Immediate Release Solid Oral Dosage Forms. The cumulative release profiles of nicotine show a dose dependent response for all nicotine levels. The on!® nicotine pouches exhibit equivalent percent nicotine release rates for each flavor variant across all nicotine levels. Furthermore, the nicotine release profiles from on!® nicotine pouches were compared to a variety of other commercially available OTDN pouches and traditional pouched smokeless tobacco products. The percent nicotine release rates were found to be dependent on the product characteristics, showing similarities and differences in the nicotine release profiles between the on!® nicotine pouches and other compared products.
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- 2021
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10. Mitochondrial Genome-Knockout Cells Demonstrate a Dual Mechanism of Action for the Electron Transport Complex I Inhibitor Mycothiazole
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Michael V. Berridge, John H. Miller, Anne C. La Flamme, Peter T. Northcote, David O’Sullivan, Praneta Joshi, Dora C. Leahy, An S. Tan, Kirsten J. Meyer, A. Jonathan Singh, and Alanna Cameron
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metabolic inhibitor ,mitochondrial electron transport complex I ,mycothiazole ,natural product ,reactive oxygen species ,Biology (General) ,QH301-705.5 - Abstract
Mycothiazole, a polyketide metabolite isolated from the marine sponge Cacospongia mycofijiensis, is a potent inhibitor of metabolic activity and mitochondrial electron transport chain complex I in sensitive cells, but other cells are relatively insensitive to the drug. Sensitive cell lines (IC50 0.36–13.8 nM) include HeLa, P815, RAW 264.7, MDCK, HeLa S3, 143B, 4T1, B16, and CD4/CD8 T cells. Insensitive cell lines (IC50 12.2–26.5 μM) include HL-60, LN18, and Jurkat. Thus, there is a 34,000-fold difference in sensitivity between HeLa and HL-60 cells. Some sensitive cell lines show a biphasic response, suggesting more than one mechanism of action. Mitochondrial genome-knockout ρ0 cell lines are insensitive to mycothiazole, supporting a conditional mitochondrial site of action. Mycothiazole is cytostatic rather than cytotoxic in sensitive cells, has a long lag period of about 12 h, and unlike the complex I inhibitor, rotenone, does not cause G2/M cell cycle arrest. Mycothiazole decreases, rather than increases the levels of reactive oxygen species after 24 h. It is concluded that the cytostatic inhibitory effects of mycothiazole on mitochondrial electron transport function in sensitive cell lines may depend on a pre-activation step that is absent in insensitive cell lines with intact mitochondria, and that a second lower-affinity cytotoxic target may also be involved in the metabolic and growth inhibition of cells.
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- 2012
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11. Nonlinear Impedance of Whole Cells Near an Electrode as a Probe of Mitochondrial Activity
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John H. Miller Jr., Jie Fang, George T. Mercier, and Akilan Palanisami
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nonlinear dielectric spectroscopy ,bioimpedance ,mitochondria ,fermentation ,Biotechnology ,TP248.13-248.65 - Abstract
By simultaneously measuring the bulk media and electrode interface voltages of a yeast (Saccharomyces cerevisiae) suspension subjected to an AC voltage, a yeast-dependent nonlinear response was found only near the current injection electrodes. Computer simulation of yeast near a current injection electrode found an enhanced voltage drop across the yeast near the electrode due to slowed charging of the electrode interfacial capacitance. This voltage drop is sufficient to induce conformation change in membrane proteins. Disruption of the mitochondrial electron transport chain is found to significantly change the measured nonlinear current response, suggesting nonlinear impedance can be used as a non-invasive probe of cellular metabolic activity.
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- 2011
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12. Nonlinear Dielectric Spectroscopy as an Indirect Probe of Metabolic Activity in Thylakoid Membrane
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John H. Miller, William R. Widger, Kimal Rajapakshe, Akilan Palanisami, and Jie Fang
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nonlinear dielectric spectroscopy ,reactive oxygen species ,whole cell biosensor ,thylakoid ,Biotechnology ,TP248.13-248.65 - Abstract
Nonlinear dielectric spectroscopy (NDS) is a non-invasive probe of cellular metabolic activity with potential application in the development of whole-cell biosensors. However, the mechanism of NDS interaction with metabolic membrane proteins is poorly understood, partly due to the inherent complexity of single cell organisms. Here we use the light-activated electron transport chain of spinach thylakoid membrane as a model system to study how NDS interacts with metabolic activity. We find protein modification, as opposed to membrane pump activity, to be the dominant source of NDS signal change in this system. Potential mechanisms for such protein modifications include reactive oxygen species generation and light-activated phosphorylation.
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- 2011
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13. Microtubule-Stabilizing Drugs from Marine Sponges: Focus on Peloruside A and Zampanolide
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John H. Miller, A. Jonathan Singh, and Peter T. Northcote
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mycalamide ,pateamine ,peloruside ,zampanolide ,microtubule stabilization ,Biology (General) ,QH301-705.5 - Abstract
Marine sponges are an excellent source of bioactive secondary metabolites with potential therapeutic value in the treatment of diseases. One group of compounds of particular interest is the microtubule-stabilizing agents, the most well-known compound of this group being paclitaxel (Taxol®), an anti-cancer compound isolated from the bark and leaves of the Pacific yew tree. This review focuses on two of the more recent additions to this important class of drugs, peloruside A and zampanolide, both isolated from marine sponges. Peloruside A was isolated from Mycale hentscheli collected in New Zealand coastal waters, and it already shows promising anti-cancer activity. Two other potent bioactive compounds with different modes of action but isolated from the same sponge, mycalamide A and pateamine, will also be discussed. The fourth compound, zampanolide, most recently isolated from the Tongan sponge Cacospongia mycofijiensis, has only recently been added to the microtubule-stabilizing group of compounds, and further work is in progress to determine its activity profile relative to peloruside A and other drugs of this class.
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- 2010
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14. Time-Correlated Vortex Tunneling in Layered Superconductors
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John H. Miller and Martha Y. S. Villagrán
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layered superconductor ,thin film ,superconducting properties ,flux vortex ,Josephson vortex ,Abrikosov vortex ,Josephson junction ,quantum tunneling ,soliton ,grain boundary ,Physics ,QC1-999 - Abstract
The nucleation and dynamics of Josephson and Abrikosov vortices determine the critical currents of layered high-Tc superconducting (HTS) thin films, grain boundaries, and coated conductors, so understanding their mechanisms is of crucial importance. Here, we treat pair creation of Josephson and Abrikosov vortices in layered superconductors as a secondary Josephson effect. Each full vortex is viewed as a composite fluid of micro-vortices, such as pancake vortices, which tunnel coherently via a tunneling matrix element. We introduce a two-terminal magnetic (Weber) blockade effect that blocks tunneling when the applied current is below a threshold value. We simulate vortex tunneling as a dynamic, time-correlated process when the current is above threshold. The model shows nearly precise agreement with voltage-current (V-I) characteristics of HTS cuprate grain boundary junctions, which become more concave rounded as temperature decreases, and also explains the piecewise linear V-I behavior observed in iron-pnictide bicrystal junctions and other HTS devices. When applied to either Abrikosov or Josephson pair creation, the model explains a plateau seen in plots of critical current vs. thickness of HTS-coated conductors. The observed correlation between theory and experiment strongly supports the proposed quantum picture of vortex nucleation and dynamics in layered superconductors.
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- 2017
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15. Hybrid Quantum Systems for Higher Temperature Quantum Information Processing
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John H. Miller, Martha Y. Suárez Villagrán, Johnathan O. Sanderson, and Jarek Wosik
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Electrical and Electronic Engineering ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2023
16. Supplementary Figures 1-2, Tables 1-3 from βII-Tubulin and βIII-Tubulin Mediate Sensitivity to Peloruside A and Laulimalide, but not Paclitaxel or Vinblastine, in Human Ovarian Carcinoma Cells
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John H. Miller, Peter T. Northcote, and Arun Kanakkanthara
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PDF file - 1.6MB
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- 2023
17. Supplementary Tables 1-4, Figures 1-4 from Peloruside- and Laulimalide-Resistant Human Ovarian Carcinoma Cells Have βI-Tubulin Mutations and Altered Expression of βII- and βIII-Tubulin Isotypes
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John H. Miller, Paraskevi Giannakakou, Ernest Hamel, Peter T. Northcote, Bronwyn Kivell, Pisana Rawson, Janet Crawford, Ada Gjyrezi, Ariane Chan, Daniel Escuin, Aurora O'Brate, Anja Wilmes, and Arun Kanakkanthara
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Supplementary Tables 1-4, Figures 1-4 from Peloruside- and Laulimalide-Resistant Human Ovarian Carcinoma Cells Have βI-Tubulin Mutations and Altered Expression of βII- and βIII-Tubulin Isotypes
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- 2023
18. Supplementary Fig. S1 from Algorithmic guided screening of drug combinations of arbitrary size for activity against cancer cells
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John H. Miller, Scott M. Lippman, Waun K. Hong, Li Mao, Gordon B. Mills, Claudio Pisano, Hai T. Tran, Reuben Lotan, Juri G. Gelovani, Andrei Y. Volgin, Paul Damien, Elmira Popova, Brittany L. Barrett, and Ralph G. Zinner
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Supplementary Fig. S1 from Algorithmic guided screening of drug combinations of arbitrary size for activity against cancer cells
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- 2023
19. Supplementary Methods from Algorithmic guided screening of drug combinations of arbitrary size for activity against cancer cells
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John H. Miller, Scott M. Lippman, Waun K. Hong, Li Mao, Gordon B. Mills, Claudio Pisano, Hai T. Tran, Reuben Lotan, Juri G. Gelovani, Andrei Y. Volgin, Paul Damien, Elmira Popova, Brittany L. Barrett, and Ralph G. Zinner
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Supplementary Methods from Algorithmic guided screening of drug combinations of arbitrary size for activity against cancer cells
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- 2023
20. Supplementary Table S1 from Algorithmic guided screening of drug combinations of arbitrary size for activity against cancer cells
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John H. Miller, Scott M. Lippman, Waun K. Hong, Li Mao, Gordon B. Mills, Claudio Pisano, Hai T. Tran, Reuben Lotan, Juri G. Gelovani, Andrei Y. Volgin, Paul Damien, Elmira Popova, Brittany L. Barrett, and Ralph G. Zinner
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Supplementary Table S1 from Algorithmic guided screening of drug combinations of arbitrary size for activity against cancer cells
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- 2023
21. Data from Algorithmic guided screening of drug combinations of arbitrary size for activity against cancer cells
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John H. Miller, Scott M. Lippman, Waun K. Hong, Li Mao, Gordon B. Mills, Claudio Pisano, Hai T. Tran, Reuben Lotan, Juri G. Gelovani, Andrei Y. Volgin, Paul Damien, Elmira Popova, Brittany L. Barrett, and Ralph G. Zinner
- Abstract
The standard treatment for most advanced cancers is multidrug therapy. Unfortunately, combinations in the clinic often do not perform as predicted. Therefore, to complement identifying rational drug combinations based on biological assumptions, we hypothesized that a functional screen of drug combinations, without limits on combination sizes, will aid the identification of effective drug cocktails. Given the myriad possible cocktails and inspired by examples of search algorithms in diverse fields outside of medicine, we developed a novel, efficient search strategy called Medicinal Algorithmic Combinatorial Screen (MACS). Such algorithms work by enriching for the fitness of cocktails, as defined by specific attributes through successive generations. Because assessment of synergy was not feasible, we developed a novel alternative fitness function based on the level of inhibition and the number of drugs. Using a WST-1 assay on the A549 cell line, through MACS, we screened 72 combinations of arbitrary size formed from a 19-drug pool across four generations. Fenretinide, suberoylanilide hydroxamic acid, and bortezomib (FSB) was the fittest. FSB performed up to 4.18 SD above the mean of a random set of cocktails or “too well” to have been found by chance, supporting the utility of the MACS strategy. Validation studies showed FSB was inhibitory in all 7 other NSCLC cell lines tested. It was also synergistic in A549, the one cell line in which this was evaluated. These results suggest that when guided by MACS, screening larger drug combinations may be feasible as a first step in combination drug discovery in a relatively small number of experiments. [Mol Cancer Ther 2009;8(3):521–32]
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- 2023
22. Synthesis and Structure-Activity Relationship Studies of C(13)-Desmethylene-(−)-Zampanolide Analogs
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Tobias Michael Brütsch, Etienne Cotter, Daniel Lucena-Agell, Mariano Redondo-Horcajo, Carolina Davies, Bernhard Pfeiffer, Simone Berardozzi, J. Fernando Díaz, John H. Miller, and Karl-Heinz Altmann
- Abstract
We have prepared a series of partially reduced or demethylated analogs of the natural microtubule stabilizer (−)-zampanolide and we have assessed their antiproliferative activity, their microtubule-binding affinity and their effects on the cellular microtubule network and on cell cycle progression. For reasons of synthetic efficiency, these analogs were derived from 13-desmethylene-(-)-zampanolide, which we had previously shown to be an equally potent cancer cell growth inhibitor as the natural product. The synthesis of all compounds was based on a unified strategy that included final formation of the macrobicyclic core by an intramolecular HWE reaction and a stereoselective aza-aldol reaction to establish the C(20) stereocenter as the key steps. All structural modifications investigated led to reduced cellular activity and lower microtubule-binding affinity compared to the parent 13-desmethylene-(–)-zampanolide, which may be ascribed to increased conformational flexibility due to the formal reduction of double bonds or the removal of the C(17)-methyl group. Notwithstanding this general trend, the cellular potency of 2,3-dihydro-13-desmethylene zampanolide as the most potent analog identified remained within a 9-fold range of that of 13-desmethylene-(–)-zampanolide (for 5 out of 6 cell lines). Notably, while the formal reduction of the C=C double bond of the enone system that is required for the covalent attachment of (−)-zampanolide to beta-tubulin caused a drop in antiproliferative activity of several hundred fold, the compound does bind to microtubules and shows the typical cellular hallmarks of a microtubule-stabilizing agent.
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- 2023
23. Synthesis and structure-activity relationship studies of C(13)-desmethylene-(−)-zampanolide analogs
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Tobias M. Brütsch, Etienne Cotter, Daniel Lucena‐Agell, Mariano Redondo‐Horcajo, Carolina Davies, Bernhard Pfeiffer, Sandro Pagani, Simone Berardozzi, J. Fernando Díaz, John H. Miller, Karl‐Heinz Altmann, Swiss National Science Foundation, ETH Zurich, Ministerio de Ciencia e Innovación (España), European Commission, Consejo Superior de Investigaciones Científicas (España), Fundación Tatiana Pérez de Guzmán el Bueno, Cotter, Etienne, Lucena-Agell, Daniel, Redondo-Horcajo, Mariano, Davies, Carolina, Pfeiffer, Bernhard, Berardozzi, Simone, Díaz, José Fernando, Miller, John H., and Altmann, Karl-Heinz
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Natural products ,Structure–activity relationships ,Zampanolide ,Organic Chemistry ,structure-activity relationships ,medicinal chemistry ,natural products ,total synthesis ,zampanolide ,Medicinal chemistry ,Total synthesis ,General Chemistry ,Catalysis - Abstract
We describe the synthesis and biochemical and cellular profiling of five partially reduced or demethylated analogs of the marine macrolide (-)-zampanolide (ZMP). These analogs were derived from 13-desmethylene-(-)-zampanolide (DM-ZMP), which is an equally potent cancer cell growth inhibitor as ZMP. Key steps in the synthesis of all compounds were the formation of the dioxabicyclo[15.3.1]heneicosane core by an intramolecular HWE reaction (67-95 % yield) and a stereoselective aza-aldol reaction with an (S)-BINOL-derived sorbamide transfer complex, to establish the C(20) stereocenter (24-71 % yield). As the sole exception, for the 5-desmethyl macrocycle, ring-closure relied on macrolactonization; however, elaboration of the macrocyclization product into the corresponding zampanolide analog was unsuccessful. All modifications led to reduced cellular activity and lowered microtubule-binding affinity compared to DM-ZMP, albeit to a different extent. For compounds incorporating the reactive enone moiety of ZMP, IC50 values for cancer cell growth inhibition varied between 5 and 133 nM, compared to 1-12 nM for DM-ZMP. Reduction of the enone double bond led to a several hundred-fold loss in growth inhibition. The cellular potency of 2,3-dihydro-13-desmethylene zampanolide, as the most potent analog identified, remained within a ninefold range of that of DM-ZMP., Chemistry - A European Journal, 29 (36), ISSN:0947-6539, ISSN:1521-3765
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- 2023
24. UHPLC-MS/MS method for the simultaneous determination of nicotine and tobacco-specific nitrosamines NNN and NNK for use in preclinical studies
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Thomas Meikopoulos, Olga Begou, Theodoros Panagoulis, Eleni Kontogiannidou, Dimitrios G. Fatouros, John H. Miller, Georgios Theodoridis, and Helen Gika
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Nicotine ,Nitrosamines ,Plant Extracts ,Tandem Mass Spectrometry ,Tobacco ,Carcinogens ,Biochemistry ,Chromatography, High Pressure Liquid ,Analytical Chemistry ,Phosphates - Abstract
A new method was developed and validated for the simultaneous determination of nicotine and tobacco-specific nitrosamines (TSNAs) 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N-nitrosonornicotine (NNN) in two different tests matrices: porcine buccal epithelium tissue and phosphate buffered saline (PBS) extracts of smokeless tobacco products. The novelty of this work is in the development of a liquid chromatography tandem mass spectrometry method that can provide simultaneous quantification of trace levels of TSNAs and high concentrations of nicotine in biological media. Precision, accuracy, and stability were evaluated during method validation to ensure the method was fit for purpose. Several sample preparation and extraction methods were evaluated to minimize matrix effects and maximize analyte recoveries. The method was accurate in the range of 81.1% – 117%; repeatability was estimated in the range of 1.5% – 13.6% across multiple concentrations. The linear regression correlation coefficient (R2) was greater than 0.9959 for all analytes, and the limit of detection (LOD) was determined for nicotine, NNK, and NNN at 1 ng/mL 0.005 ng/mL, and 0.006 ng/ mL, respectively. Our method was found to be appropriate for the analysis of nicotine, NNN, and NNK in the porcine buccal epithelium and PBS extracts of smokeless tobacco products. Graphical abstract
- Published
- 2022
25. A 6-month inhalation toxicology study in Apoe−/− mice demonstrates substantially lower effects of e-vapor aerosol compared with cigarette smoke in the respiratory tract
- Author
-
Walter K. Schlage, Julia Hoeng, Dariusz Peric, Nicolas Sierro, John H. Miller, Ee Tsin Wong, Blaine Phillips, Justyna Szostak, Jingjie Zhang, Emmanuel Guedj, Patrick Vanscheeuwijck, Jovan Simicevic, Tom Lee, Manuel C. Peitsch, Patrice Leroy, Remi Dulize, Maica Corciulo, Oksana Lavrynenko, Yang Xiang, Kyeonghee Monica Lee, David Bornand, Bjoern Titz, Sin Kei Wong, Karsta Luettich, Mohamed Amin Choukrallah, Arkadiusz K. Kuczaj, Guo Jie Loh, Thomas Schneider, Nikolai V. Ivanov, Mehdi Auberson, Celine Merg, and Ansgar Buettner
- Subjects
0301 basic medicine ,Health, Toxicology and Mutagenesis ,010501 environmental sciences ,Electronic Nicotine Delivery Systems ,Toxicology ,medicine.disease_cause ,01 natural sciences ,law.invention ,Nicotine ,Mice ,law ,Smoke ,Respiratory system ,Electronic cigarette ,Lung ,COPD ,Inhalation Exposure ,Smoking ,General Medicine ,Tobacco Products ,respiratory system ,Respiratory Function Tests ,medicine.anatomical_structure ,Female ,Irritation ,medicine.drug ,medicine.medical_specialty ,complex mixtures ,Organ Toxicity and Mechanisms ,03 medical and health sciences ,Apolipoproteins E ,Internal medicine ,Tobacco ,medicine ,Animals ,0105 earth and related environmental sciences ,Emphysema ,Inflammation ,Aerosols ,business.industry ,medicine.disease ,030104 developmental biology ,Endocrinology ,business ,Transcriptome ,Oxidative stress ,Respiratory tract - Abstract
Cigarette smoking is the major cause of chronic obstructive pulmonary disease. Considerable attention has been paid to the reduced harm potential of nicotine-containing inhalable products such as electronic cigarettes (e-cigarettes). We investigated the effects of mainstream cigarette smoke (CS) and e-vapor aerosols (containing nicotine and flavor) generated by a capillary aerosol generator on emphysematous changes, lung function, and molecular alterations in the respiratory system of female Apoe−/− mice. Mice were exposed daily (3 h/day, 5 days/week) for 6 months to aerosols from three different e-vapor formulations—(1) carrier (propylene glycol and vegetable glycerol), (2) base (carrier and nicotine), or (3) test (base and flavor)—or to CS from 3R4F reference cigarettes. The CS and base/test aerosol concentrations were matched at 35 µg nicotine/L. CS exposure, but not e-vapor exposure, led to impairment of lung function (pressure–volume loop area, A and K parameters, quasi-static elastance and compliance) and caused marked lung inflammation and emphysematous changes, which were confirmed histopathologically and morphometrically. CS exposure caused lung transcriptome (activation of oxidative stress and inflammatory responses), lipidome, and proteome dysregulation and changes in DNA methylation; in contrast, these effects were substantially reduced in response to the e-vapor aerosol exposure. Compared with sham, aerosol exposure (carrier, base, and test) caused a slight impact on lung inflammation and epithelia irritation. Our results demonstrated that, in comparison with CS, e-vapor aerosols induced substantially lower biological and pathological changes in the respiratory tract associated with chronic inflammation and emphysema. Supplementary Information The online version supplementary material available at 10.1007/s00204-021-03020-4.
- Published
- 2021
26. Quantum phase transitions of strongly correlated metals
- Author
-
Nikolaos Mitsakos, Martha Villagran, and John H. Miller
- Subjects
Physics ,Quantum phase transition ,Condensed matter physics ,0103 physical sciences ,02 engineering and technology ,General Medicine ,021001 nanoscience & nanotechnology ,010306 general physics ,0210 nano-technology ,01 natural sciences - Abstract
In this article, we discuss several aspects of the quantum phase transition, with special emphasis on the metalinsulator transition. We start with a review of key experimental and theoretical works and then discuss how doping a system reduces the critical temperature of the overall phase transition. Although many aspects of the quantum phase transition still remain an open problem, onsiderable progress has been made in revealing the underlying physics, both theoretically and experimentally.
- Published
- 2020
27. Registration of ‘StandClear CLP’ hard red winter wheat
- Author
-
S. Gale, Ron Ramsfield, Yue Jin, Jed O. Eberly, D. L. Holen, Jessica A. Torrion, Ken D. Kephart, D. L. Nash, J. P. Cook, John H. Miller, Chengci Chen, Peggy F. Lamb, Jim E. Berg, Phil L. Bruckner, Edward S. Davis, Gautam P. Pradhan, Vincent H. Smith, and Xianming Chen
- Subjects
Agronomy ,Winter wheat ,Genetics ,Biology ,Agronomy and Crop Science - Published
- 2020
28. Synthesis of Novel Glycolipid Mimetics of Heparan Sulfate and Their Application in Colorectal Cancer Treatment in a Mouse Model
- Author
-
Sam Spijkers‐Shaw, Katrin Campbell, Nicholas J. Shields, John H. Miller, Phillip M. Rendle, Wanting Jiao, Sarah L. Young, and Olga V. Zubkova
- Subjects
Mice ,Neovascularization, Pathologic ,Organic Chemistry ,Animals ,Heparitin Sulfate ,General Chemistry ,Glycolipids ,Colorectal Neoplasms ,Biochemistry ,Uncategorized - Abstract
Heparan sulfate (HS) is a highly sulfated natural carbohydrate that plays crucial roles in cancer, inflammation, and angiogenesis. Heparanase (HPSE) is the sole HS degrading endoglycosidase that cleaves HS at structure-dependent sites along the polysaccharide chain. Overexpression of HPSE by cancer cells correlates with increased tumor size and enhanced metastasis. Previously we have shown that a tetramer HS mimetic is a potent HPSE inhibitor displaying remarkable anticancer activity in vivo. Building on that work, we report the synthesis and testing of a novel library of single entity trimer glycolipid mimetics that effectively inhibit HPSE at low nanomolar concentrations. A lipophilic arm was introduced to assess whether an improvement of pharmacokinetics and plasma residence time would offset the reduction in charge and multivalency. Preclinical tests in a mouse syngeneic model showed effective tumor growth inhibition by the tetramer but not the trimer glycomimetic.
- Published
- 2022
- Full Text
- View/download PDF
29. Hamigeran G Does Not Affect Golgi Structure or Function in HEK293 Cells
- Author
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Euan R. Russell, A. Jonathan Singh, Catrina Olivera, John H. Miller, and Peter T. Northcote
- Subjects
0303 health sciences ,biology ,010405 organic chemistry ,Chemistry ,HEK 293 cells ,Saccharomyces cerevisiae ,Golgi apparatus ,biology.organism_classification ,Endocytosis ,01 natural sciences ,Yeast ,0104 chemical sciences ,Cell biology ,03 medical and health sciences ,symbols.namesake ,Secretory protein ,Mechanism of action ,medicine ,symbols ,medicine.symptom ,Function (biology) ,030304 developmental biology - Abstract
The hamigerans are diterpenoid secondary metabolites isolated from the New Zealand marine sponge Hamigera tarangaensis. Of all the hamigerans that have been isolated and characterised at Victoria University of Wellington, hamigeran G showed the most potent anti-proliferative activity against a mammalian cancer cell line. We previously reported that it might be targeting the Golgi network of cells based on a chemical genomic screen on yeast (Saccharomyces cerevisiae). Here, we investigated the effects of hamigeran G on the Golgi network of mammalian cells and showed that it did not have a significant effect on Golgi apparatus morphology or Golgi network functions such as protein secretion and endocytosis. Results of this study, therefore, conclude that the Golgi network is unlikely to be the primary target of hamigeran G's anti-proliferative activity. Further work is needed to fully elucidate the mechanism of action and target(s) of hamigeran G.
- Published
- 2019
30. Assessing the performance of pea and lentil at different seeding densities as trap crops for the management of wireworms in spring wheat
- Author
-
Gadi V. P. Reddy, John H. Miller, Shabeg S. Briar, Anamika Sharma, and Ramandeep Kaur Sandhi
- Subjects
0106 biological sciences ,geography ,geography.geographical_feature_category ,Pulse crop ,Biology ,010603 evolutionary biology ,01 natural sciences ,Cultural control ,010602 entomology ,Agronomy ,Insect Science ,Trap crop ,Spring (hydrology) ,Seeding ,Agronomy and Crop Science - Published
- 2018
31. The mixed kappa and delta opioid receptor agonist, MP1104, attenuates chemotherapy-induced neuropathic pain
- Author
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Susruta Majumdar, Rajendra Uprety, Bronwyn M. Kivell, Amy F. Alder, Kelly F. Paton, Diana V. Atigari, Brittany Scouller, John H. Miller, and András Váradi
- Subjects
0301 basic medicine ,Agonist ,Male ,medicine.drug_class ,Antineoplastic Agents ,Pharmacology ,κ-opioid receptor ,Article ,δ-opioid receptor ,Rats, Sprague-Dawley ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,Mice ,0302 clinical medicine ,Opioid receptor ,Receptors, Opioid, delta ,Medicine ,Animals ,Dose-Response Relationship, Drug ,business.industry ,Receptors, Opioid, kappa ,Chronic pain ,medicine.disease ,Rats ,Analgesics, Opioid ,Mice, Inbred C57BL ,030104 developmental biology ,Morphinans ,Neuropathic pain ,Morphine ,Neuralgia ,Female ,business ,Oxycodone ,030217 neurology & neurosurgery ,Injections, Intraperitoneal ,medicine.drug - Abstract
Effective treatments for chronic pain without abuse liability are urgently needed. One in 5 adults suffer chronic pain and half of these patients report inefficient treatment. Mu opioid receptor agonists (MOP), including oxycodone, tramadol and morphine, are often prescribed to treat chronic pain, however, use of drugs targeting MOP can lead to drug dependency, tolerance and overdose deaths. Kappa opioid receptor (KOP) agonists have antinociceptive effects without abuse potential; however, they have not been utilised clinically due to dysphoria and sedation. We hypothesise that mixed opioid receptor agonists targeting the KOP and delta opioid receptor (DOP) would have a wider therapeutic index, with the rewarding effects of DOP negating the negative effects of KOP. MP1104, an analogue of 3-Iodobenzoyl naltrexamine, is a novel mixed opioid receptor agonist with potent antinociceptive effects mediated via KOP and DOP in mice without rewarding or aversive effects. In this study, we show MP1104 has potent, long-acting antinociceptive effects in the warm-water tail-withdrawal assay in male and female mice and rats; and is longer acting than morphine. In the paclitaxel-induced neuropathic pain model in mice, MP1104 reduced both mechanical and cold allodynia and unlike morphine, did not produce tolerance when administered daily for 23 days. Moreover, MP1104 did not induce sedative effects in the open-field locomotor activity test, respiratory depression in mice using whole-body plethysmography, or have cross-tolerance with morphine. This data supports the therapeutic development of mixed opioid receptor agonists, particularly mixed KOP/DOP agonists, as non-addictive pain medications with reduced tolerance.
- Published
- 2020
32. Coherent, time-correlated tunneling of density wave electrons
- Author
-
John H Miller and Martha Y Suárez-Villagrán
- Subjects
History ,Condensed Matter::Superconductivity ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Computer Science Applications ,Education - Abstract
A growing body of evidence reveals that charge density wave (CDW) transport is a high-temperature cooperative quantum phenomenon. According to the time-correlated soliton tunneling (ST) model, quantum solitons, or electron-phonon correlates within the CDW condensate, act much like electrons tunneling through a Coulomb-blockade tunnel junction. Pair creation of charged fluidic soliton droplets is prevented by their electrostatic energy below a Coulomb-blockade threshold electric field. Above threshold, the quantum fluid flows in a periodic fashion, via a hybrid between Zener-like and coherent Josephson-like tunneling. We summarize the time-correlated ST model and compare model simulations with experiment. The ST model shows excellent agreement with coherent voltage oscillations, and with CDW current-voltage characteristics. Finally, we discuss implications for physics and potential applications.
- Published
- 2022
33. Tracking Robot Location for Non-Destructive Evaluation of Double-Shell Tanks
- Author
-
Emily Carter, Christopher Cree, John H. Miller, Changki Mo, and Heng Wang
- Subjects
Decision support system ,Situation awareness ,Computer science ,Real-time computing ,Shell (computing) ,laser ranging ,02 engineering and technology ,Tracking (particle physics) ,01 natural sciences ,lcsh:Technology ,computer vision ,lcsh:Chemistry ,image analysis ,0202 electrical engineering, electronic engineering, information engineering ,General Materials Science ,Instrumentation ,lcsh:QH301-705.5 ,Fluid Flow and Transfer Processes ,Data collection ,lcsh:T ,Process Chemistry and Technology ,020208 electrical & electronic engineering ,010401 analytical chemistry ,General Engineering ,lcsh:QC1-999 ,0104 chemical sciences ,Computer Science Applications ,lcsh:Biology (General) ,lcsh:QD1-999 ,Mockup ,lcsh:TA1-2040 ,Storage tank ,Robot ,lcsh:Engineering (General). Civil engineering (General) ,lcsh:Physics - Abstract
(1) Background: Non-destructive evaluation of double-shell nuclear-waste storage tanks at the U.S. Department of Energy&rsquo, s Hanford site requires a robot to navigate a network of air slots in the confined space between primary and secondary tanks. Situational awareness, data collection, and data interpretation require continuous tracking of the robot&rsquo, s location. (2) Methods: Robot location is continuously monitored using video image analysis for short distances and laser ranging for absolute location. (3) Results: The technique was demonstrated in our laboratory using a mockup of air slot and robot. (4) Conclusions: Location tracking and display provide decision support to inspectors and lay the groundwork for automated data collection.
- Published
- 2020
- Full Text
- View/download PDF
34. Unusually thick metal-insulator domain walls around the Mott point
- Author
-
Tsung-Han Lee, Nikolaos Mitsakos, Martha Y. Suárez-Villagrán, Vladimir Dobrosavljevic, John H. Miller, and Eduardo Miranda
- Subjects
Physics ,Feature (archaeology) ,Condensed matter physics ,Strongly Correlated Electrons (cond-mat.str-el) ,Model study ,FOS: Physical sciences ,01 natural sciences ,010305 fluids & plasmas ,Condensed Matter - Strongly Correlated Electrons ,Phase (matter) ,0103 physical sciences ,Domain (ring theory) ,Magnetic frustration ,Point (geometry) ,Condensed Matter::Strongly Correlated Electrons ,Metal insulator ,010306 general physics - Abstract
Many Mott systems feature a first-order metal-insulator transition at finite temperatures, with an associated phase coexistence region displaying inhomogeneities and local phase separation. Here one typically finds "bubbles" or domains of the respective phases, which are separated by surprisingly thick, or fat, domain walls, as revealed both by imaging experiments and recent theoretical modeling. To gain insight into this unexpected behavior, we perform a systematic model study of the structure of such metal-insulator domain walls around the Mott point, within the dynamical mean-field theory framework. Our study reveals that a mechanism producing such "fat" domain walls can be traced to strong magnetic frustration, which is expected to be a robust feature of "spin-liquid" Mott systems.
- Published
- 2020
- Full Text
- View/download PDF
35. Influence of Electron–Holes on DNA Sequence-Specific Mutation Rates
- Author
-
Martha Y. Suárez-Villagrán, Ricardo B. R. Azevedo, and John H. Miller
- Subjects
DNA Replication ,0301 basic medicine ,Mutation rate ,Mitochondrial DNA ,hypervariable segment I ,oxidation ,electron–hole ,Electrons ,mitochondrial DNA ,Biology ,DNA, Mitochondrial ,Evolution, Molecular ,03 medical and health sciences ,Mutation Rate ,tautomer ,Molecular evolution ,human genome ,Genetics ,Humans ,context-dependent mutation ,cancer ,mutation rate bias ,Ecology, Evolution, Behavior and Systematics ,mtDNA control region ,Base Sequence ,Genome, Human ,Mutation Accumulation ,030104 developmental biology ,Mutagenesis ,Evolutionary biology ,Mutation (genetic algorithm) ,DNA methylation ,CpG Islands ,Human genome ,Research Article - Abstract
Biases in mutation rate can influence molecular evolution, yielding rates of evolution that vary widely in different parts of the genome and even among neighboring nucleotides. Here, we explore one possible mechanism of influence on sequence-specific mutation rates, the electron–hole, which can localize and potentially trigger a replication mismatch. A hole is a mobile site of positive charge created during one-electron oxidation by, for example, radiation, contact with a mutagenic agent, or oxidative stress. Its quantum wavelike properties cause it to localize at various sites with probabilities that vary widely, by orders of magnitude, and depend strongly on the local sequence. We find significant correlations between hole probabilities and mutation rates within base triplets, observed in published mutation accumulation experiments on four species of bacteria. We have also computed hole probability spectra for hypervariable segment I of the human mtDNA control region, which contains several mutational hotspots, and for heptanucleotides in noncoding regions of the human genome, whose polymorphism levels have recently been reported. We observe significant correlations between hole probabilities, and context-specific mutation and substitution rates. The correlation with hole probability cannot be explained entirely by CpG methylation in the heptanucleotide data. Peaks in hole probability tend to coincide with mutational hotspots, even in mtDNA where CpG methylation is rare. Our results suggest that hole-enhanced mutational mechanisms, such as oxidation-stabilized tautomerization and base deamination, contribute to molecular evolution.
- Published
- 2018
36. Simulation As A Tool In Designing And Evaluating A Robotic Apple Harvesting System
- Author
-
Manoj Karkee, John H. Miller, Heng Wang, Cameron J. Hohimer, Changki Mo, and Santosh Bhusal
- Subjects
Modeling and simulation ,0209 industrial biotechnology ,020901 industrial engineering & automation ,Control and Systems Engineering ,Computer science ,Robustness (computer science) ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Control engineering ,04 agricultural and veterinary sciences ,02 engineering and technology ,Workspace ,Manipulator - Abstract
During the past several years, significant effort has been made to develop a robotic system to harvest fresh market apples in a modern apple orchard at Washington State University (WSU). This system has gone through several modifications to achieve enhanced system accuracy, speed, robustness, and reduction of fruit damage and cost. However, due to the short window of apple picking each year and the challenging environment of the orchard, those modifications had limited success in improving the robotic systems performance even with extensive laboratory testing before each field trial. To further assess potential problems, better prepare for the field trial, and make best use of the limited time in the field, in silico testing is necessary in addition to laboratory testing. In this work, computer modeling and simulation were used to help identify potential problem in the robotic system, evaluate the effectiveness of the newly made modifications, and aid in both algorithm development and configuration design of the system. By doing simulations with field study data and workspace analysis of the system, we developed a novel algorithm to improve the reachability of the picking arm. We also concluded that the overlap of the arm’s workspace and the fruit space is the key in deciding the reachability of the manipulator instead of the volume of arm’s workspace.
- Published
- 2018
37. Method for the Determination of Carbonyl Compounds in E-Cigarette Aerosols
- Author
-
John H. Miller, James A. Skapars, Jason W. Flora, Peter J. Lipowicz, Anderson Adam, James W. Wilkinson, and Celeste T. Wilkinson
- Subjects
Hot Temperature ,Formaldehyde ,010501 environmental sciences ,Electronic Nicotine Delivery Systems ,Mass spectrometry ,01 natural sciences ,Article ,Gas Chromatography-Mass Spectrometry ,Analytical Chemistry ,chemistry.chemical_compound ,Cigarette smoke ,Crotonaldehyde ,0105 earth and related environmental sciences ,Aerosols ,Aldehydes ,Chromatography ,010401 analytical chemistry ,Acrolein ,Acetaldehyde ,General Medicine ,Equipment Design ,Models, Theoretical ,0104 chemical sciences ,Aerosol ,chemistry ,Gas chromatography–mass spectrometry - Abstract
Low levels of thermal degradation products such as carbonyls (formaldehyde, acetaldehyde, acrolein, crotonaldehyde) have been reported in e-cigarette aerosols. The collection and analysis of e-cigarette aerosol carbonyls are often adapted from methods developed for tobacco cigarette smoke. These methodologies are often not sensitive enough to detect low carbonyl levels in e-cigarette aerosols. One objective of this work was to develop and validate a rapid, selective and sensitive ultra-performance liquid chromatography with mass spectrometry method optimized for analysis of carbonyls in e-cigarette aerosols. Aerosols were trapped in 20-puff collections, 4-s durations, 55-mL volumes, 30-s intervals, square wave puff profiles. Collection apparatus involved a linear smoking machine with Cambridge filter pad followed by a glass impinger containing acidified 2,4-dinitrophenylhydrazine. This method showed limits of quantitation and detection of 0.016 and 0.003 µg puff-1, respectively, and run time of 4 min. Six e-cigarettes were evaluated (five devices each). All contained measurable levels of carbonyls. Levels were mostly well below those in conventional cigarettes. However, for some e-cigarettes, formaldehyde levels were above those for tobacco cigarettes (highest at 14.1 µg puff-1). Temperatures related to carbonyl yields in e-cigarette aerosols were explored to better understand carbonyl formation: formation of formaldehyde is low at temperatures below 350°C.
- Published
- 2017
38. Possible transport evidence for three-dimensional topological superconductivity in doped β-PdBi2
- Author
-
Pavan Hosur, John H. Miller, Ayo Kolapo, and Tingxin Li
- Subjects
0301 basic medicine ,Quantum phase transition ,Science ,Topology ,Article ,Superconducting properties and materials ,03 medical and health sciences ,0302 clinical medicine ,Condensed Matter::Superconductivity ,Topological insulators ,Electronic band structure ,Topological matter ,Surface states ,Superconductivity ,Physics ,Multidisciplinary ,Materials science ,MAJORANA ,030104 developmental biology ,Topological insulator ,Pairing ,State of matter ,Medicine ,030217 neurology & neurosurgery - Abstract
Interest in topological states of matter burgeoned over a decade ago with the theoretical prediction and experimental detection of topological insulators, especially in bulk three-dimensional insulators that can be tuned out of it by doping. Their superconducting counterpart, the fully-gapped three-dimensional time-reversal-invariant topological superconductors, have evaded discovery in bulk intrinsic superconductors so far. The recently discovered topological metal β-PdBi2 is a unique candidate for tunable bulk topological superconductivity because of its intrinsic superconductivity and spin-orbit-coupling. In this work, we provide experimental transport signatures consistent with fully-gapped 3D time-reversal-invariant topological superconductivity in K-doped β-PdBi2. In particular, we find signatures of odd-parity bulk superconductivity via upper-critical field and magnetization measurements— odd-parity pairing can be argued, given the band structure of β-PdBi2, to result in 3D topological superconductivity. In addition, Andreev spectroscopy reveals surface states protected by time-reversal symmetry which might be possible evidence of Majorana surface states (Majorana cone). Moreover, we find that the undoped bulk system is a trivial superconductor. Thus, we discover β-PdBi2 as a unique bulk material that, on doping, can potentially undergo an unprecedented topological quantum phase transition in the superconducting state.
- Published
- 2019
39. The two-dimensional disordered Mott metal-insulator transition
- Author
-
Vladimir Dobrosavljevic, Nikolaos Mitsakos, John H. Miller, Tsung-Han Lee, Martha Y. Suárez-Villagrán, and Eduardo Miranda
- Subjects
Physics ,Condensed Matter::Quantum Gases ,Anderson localization ,Spinodal ,Condensed matter physics ,Electronic correlation ,Hubbard model ,Strongly Correlated Electrons (cond-mat.str-el) ,Quantum Monte Carlo ,FOS: Physical sciences ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Mott transition ,Condensed Matter - Strongly Correlated Electrons ,0103 physical sciences ,Thermodynamic limit ,Condensed Matter::Strongly Correlated Electrons ,Metal–insulator transition ,010306 general physics ,0210 nano-technology - Abstract
We studied several aspects of the Mott metal-insulator transition in the disordered case. The model on which we based our analysis is the disordered Hubbard model, which is the simplest model capable of capturing the Mott metal-insulator transition. We investigated this model through statistical dynamical mean-field theory (statDMFT). This theory is a natural extension of dynamical mean-field theory (DMFT), which has been used with relative success in the past several years with the purpose of describing the Mott transition in the clean case. As is the case for the latter theory, statDMFT incorporates the electronic correlation effects only in their local manifestations. Disorder, on the other hand, is treated in such a way as to incorporate Anderson localization effects. With this technique, we analyzed the disordered two-dimensional Mott transition, using the quantum Monte Carlo algorithm to solve the associated single-impurity problems. We found spinodal lines at which the metal and insulator ceased to be metastable. We also studied spatial fluctuations of local quantities, such as self-energy and local Green's function, and showed the appearance of metallic regions within the insulator and vice versa. We carried out an analysis of finite-size effects and showed that, in agreement with the theorems of Imry and Ma [Y. Imry and S. K. Ma, Phys. Rev. Lett. 35, 1399 (1975).], the first-order transition is smeared in the thermodynamic limit. We analyzed transport properties by means of a mapping to a random classical resistor network and calculated both the average current and its distribution across the metal-insulator transition.
- Published
- 2019
- Full Text
- View/download PDF
40. Nicotine-related impurities in e-cigarette cartridges and refill e-liquids
- Author
-
Jason W. Flora, John H. Miller, Celeste T. Wilkinson, Kathleen M. Sink, and Diana L. McKinney
- Subjects
Nornicotine ,Chromatography ,010401 analytical chemistry ,Clinical Biochemistry ,Pharmaceutical Science ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Analytical Chemistry ,Nicotine ,03 medical and health sciences ,Cartridge ,chemistry.chemical_compound ,0302 clinical medicine ,chemistry ,Transfer efficiency ,medicine ,030212 general & internal medicine ,Related impurities ,Cotinine ,medicine.drug - Abstract
The nicotine used in e-cigarettes and refill e-liquids is extracted from tobacco, and its purity can vary depending upon manufacturer and grade. The US and European Pharmacopoeias make recommendations for the purity of nicotine intended for pharmaceuticals; however, there is no official purity recommendation for nicotine used in e-cigarettes. To date, there are few published reports on nicotine-related impurities in e-cigarettes and refill e-liquids. The objective of this work was to develop a sensitive, selective, and robust analytical method for the quantitation of nicotine-related impurities in e-vapor products and to evaluate the nicotine-related impurities in a variety of commercial e-cigarette cartridges (n = 10) and refill e-liquids (n = 10). Nicotine-N-oxide, nornicotine, mysomine, and cotinine were observed to increase with time during stability studies. This method was also applied to estimate the transfer efficiency of nicotine-related impurities to the aerosol. Most of the impurities w...
- Published
- 2016
41. Prototype e-cigarette and the capillary aerosol generator (CAG) comparison and qualification for use in subchronic inhalation exposure testing
- Author
-
John H. Miller, Michael J. Oldham, Willie J. McKinney, Tucker Christopher S, David B. Kane, and Michael S. Werley
- Subjects
Inhalation exposure ,Chromatography ,Inhalation ,Capillary action ,Acrolein ,Condensation ,Formaldehyde ,Acetaldehyde ,010501 environmental sciences ,01 natural sciences ,Pollution ,Aerosol ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,chemistry ,Environmental Chemistry ,Organic chemistry ,General Materials Science ,030212 general & internal medicine ,0105 earth and related environmental sciences - Abstract
Our objective was to evaluate the suitability of using a capillary aerosol generator (CAG) instead of using e-cigarette devices in 90-day or longer inhalation studies. Aerosol characteristics for both the CAG (which uses heat to produce a condensation aerosol) and e-cigarette generators have been previously reported, but a side-by-side comparison with the identical formulation has not been reported. Aerosols from both devices were analyzed immediately after generation for chemicals in the formulation (propylene glycol [PG], glycerin, water, and nicotine), selected carbonyls (acetaldehyde, acrolein, and formaldehyde) by ultra-performance liquid chromatography with ultraviolet detection (UPLC-UV), and a chemical fingerprint analysis using gas chromatography-mass spectroscopy (GC-MS). Aerosol capture methods for chemical analysis included Cambridge filter pads or two impingers in series each containing solution to trap and stabilize selected carbonyl compounds. Particle size distribution (cascade imp...
- Published
- 2016
42. Registration of ‘Northern’ Hard Red Winter Wheat
- Author
-
Robert N. Stougaard, Guihua Bai, Phil L. Bruckner, Timothy D. Murray, S. Gale, W. E. Grey, James A. Kolmer, David M. Wichman, D. L. Nash, Gautam P. Pradhan, Ken D. Kephart, Jim E. Berg, D. Gettel, Peggy F. Lamb, John H. Miller, Yue Jin, and Xianming Chen
- Subjects
0106 biological sciences ,Agricultural experiment station ,Agronomy ,Winter wheat ,040103 agronomy & agriculture ,Genetics ,0401 agriculture, forestry, and fisheries ,04 agricultural and veterinary sciences ,Biology ,01 natural sciences ,Agronomy and Crop Science ,010606 plant biology & botany - Abstract
Montana Agricultural Experiment Station; Montana Wheat and Barley Committee; Hatch project (MONB00298)
- Published
- 2016
43. Synthesis of a simplified triazole analogue of pateamine A
- Author
-
A. Hemi Cumming, Sarah L. Brown, Claire Cuyamendous, Paul H. Teesdale-Spittle, Jessica J. Field, John H. Miller, Xu Tao, and Joanne E. Harvey
- Subjects
Azides ,Stereochemistry ,Triazole ,Antineoplastic Agents ,Chemistry Techniques, Synthetic ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Catalysis ,Article ,chemistry.chemical_compound ,Eukaryotic translation ,Moiety ,Physical and Theoretical Chemistry ,Cytotoxicity ,Thiazole ,Natural product ,010405 organic chemistry ,Organic Chemistry ,Triazoles ,Cycloaddition ,0104 chemical sciences ,Thiazoles ,chemistry ,Epoxy Compounds ,Macrolides ,Target protein ,Copper - Abstract
Pateamine A is a naturally occurring metabolite extracted from the marine sponge Mycale hentscheli. It exhibits potent cytotoxicity towards cancer cell lines and has been shown to target protein translation initiation via inhibition of the function of eukaryotic initiation factor 4A proteins. We have synthesised a simplified analogue of pateamine A, consisting of the skeletal core of the natural product but with the thiazole heterocycle replaced by a triazole. The convergent design of the synthesis features a base-induced opening of a δ-valerolactone to access the Z,E-dienoate moiety, Julia-Kocienski olefination and copper-catalysed azide-alkyne cycloaddition. Bioactivity testing of the simplified pateamine A analogue (3) indicated a significant reduction in cytotoxicity, compared to natural pateamine A. We propose that this reduced activity is due mainly to the substitution of the thiazole for the triazole heterocycle. This supports the hypothesis that the thiazole of pateamine A is important for binding to its biological target.
- Published
- 2016
44. Reduced Glutathione Peroxidase Activity Predicts Increased Cardiovascular Risk Following an Acute Coronary Syndrome
- Author
-
Ana Holley, John H. Miller, Alexander Sasse, Scott A. Harding, and Peter D. Larsen
- Subjects
medicine.medical_specialty ,Acute coronary syndrome ,lcsh:Diseases of the circulatory (Cardiovascular) system ,cardiac event ,lcsh:Medicine ,medicine.disease_cause ,Gastroenterology ,Internal medicine ,medicine ,oxidative stress ,acute coronary syndromes ,Myocardial infarction ,cardiovascular diseases ,Prospective cohort study ,chemistry.chemical_classification ,business.industry ,Glutathione peroxidase ,lcsh:R ,Area under the curve ,medicine.disease ,Surgery ,chemistry ,lcsh:RC666-701 ,Heart failure ,business ,Mace ,Oxidative stress - Abstract
Background: Glutathione peroxidase (GPx) is an antioxidant enzyme that comprises a primary defence against oxidative stress. Deficiencies in GPx have been associated with progression of atherosclerosis and arterial thrombosis. However, the relationship between GPx activity and clinical outcomes in acute coronary syndromes (ACS) remains controversial. This study examined the relationship between plasma GPx activity and subsequent major adverse cardiovascular events (MACE) in ACS patients.Method: In this prospective cohort study, 262 ACS patients had their plasma GPx activity measured using a colourimetric enzyme assay. Patient demographics, clinical variables and MACE, a composite of death, non-fatal myocardial infarction, ischaemic stroke and acute heart failure, were collected.Results: At 1 year follow-up, 34 (13%) patients experienced MACE. When the MACE rate was examined by quartiles of GPx activity, a significant decrease in MACE was demonstrated with increasing quartiles of GPx activity (P = 0.04). The event rate for patients in the lowest quartile of GPx activity was 19.6% compared to 7.9% for the upper quartile. Levels of GPx activity were significantly lower in diabetic patients compared to non-diabetic patients (P = 0.02), and lower in males compared to females (P = 0.03). GPx activity was a moderate predictor of MACE by receiver operator characteristic analysis with an area under the curve of 0.62 (P = 0.02).Conclusion: We have demonstrated that lower levels of GPx activity are associated with an increased risk of MACE at 1 year following an ACS. Low levels of GPx activity may represent a decreased defence against oxidant-mediated cardiovascular damage.
- Published
- 2016
45. Method development and validation of dissolution testing for nicotine release from smokeless tobacco products using flow-through cell apparatus and UPLC-PDA
- Author
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Yezdi B. Pithawalla, Karl A. Wagner, Tim Danielson, John H. Miller, Fadi Aldeek, Celeste T. Wilkinson, and Anthony P. Brown
- Subjects
Nicotine ,Tobacco, Smokeless ,Uplc pda ,Clinical Biochemistry ,Models, Biological ,030226 pharmacology & pharmacy ,01 natural sciences ,Biochemistry ,Chemistry Techniques, Analytical ,Analytical Chemistry ,03 medical and health sciences ,0302 clinical medicine ,Limit of Detection ,medicine ,Humans ,Dissolution testing ,Saliva ,Chromatography, High Pressure Liquid ,Chromatography ,Chemistry ,010401 analytical chemistry ,technology, industry, and agriculture ,Flow through cell ,Reproducibility of Results ,Equipment Design ,Cell Biology ,General Medicine ,Method development ,0104 chemical sciences ,stomatognathic diseases ,Chewing tobacco ,Smokeless tobacco ,Snus ,Linear Models ,medicine.drug - Abstract
Developing dissolution testing methods to measure the nicotine release profiles from smokeless tobacco products is valuable for product assessment and product-to-product comparisons. In this work, we developed a robust dissolution method to study the in vitro release of nicotine from smokeless tobacco products using the U.S. Pharmacopeia flow-through cell dissolution apparatus 4 (USP-4). We further developed and validated a sensitive Ultra Performance Liquid Chromatography coupled to Photodiode Array detector (UPLC-PDA) method for the accurate quantitation of the released nicotine into artificial saliva, which is our selected dissolution medium. We have successfully shown the applicability of the validated method by investigating the release profiles of nicotine from various commercial and CORESTA reference smokeless tobacco products [CRP 1.1 (Swedish-style snus pouch), CRP 2.1 (American-style loose moist snuff), CRP 4 (loose-leaf chewing tobacco) and CRP 4.1 (chopped loose-leaf chewing tobacco)]. Nicotine release profiles were analyzed by calculating the difference factor (f1) and similarity factor (f2) by adopting a methodology referenced in the Guidance for Industry from FDA's Center for Drug Evaluation and Research (CDER) and by fitting the release profile curves using a first order kinetic model. Nicotine release was found to be dependent on the form and cut of the smokeless tobacco products, with a slower release observed for snus and loose-leaf, compared to chopped and loose moist snuff smokeless tobacco. This dissolution methodology can be extended to measure and compare release of other constituents from smokeless tobacco products and has the potential for method standardization.
- Published
- 2020
46. Dendrimer Heparan Sulfate Glycomimetics: Potent Heparanase Inhibitors for Anticancer Therapy
- Author
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Yassir A. Ahmed, Raymond A. A. Smith, Victor Nurcombe, Olga V. Zubkova, John H. Miller, Sophia-Louise Noble, Jeremy E. Turnbull, Peter C. Tyler, Scott E. Guimond, Marina Weissmann, and Israel Vlodavsky
- Subjects
0301 basic medicine ,60199 Biochemistry and Cell Biology not elsewhere classified ,Cell signaling ,Dendrimers ,Angiogenesis ,Angiogenesis Inhibitors ,Antineoplastic Agents ,Biochemistry ,Extracellular matrix ,03 medical and health sciences ,chemistry.chemical_compound ,Inhibitory Concentration 50 ,Mice ,0302 clinical medicine ,Glycomimetic ,Biomimetic Materials ,Cell Line, Tumor ,Animals ,Humans ,Heparanase ,Glycosides ,Enzyme Inhibitors ,Cytotoxicity ,Glucuronidase ,Molecular Structure ,Cell migration ,General Medicine ,Heparan sulfate ,Xenograft Model Antitumor Assays ,030104 developmental biology ,chemistry ,FOS: Biological sciences ,030220 oncology & carcinogenesis ,Cancer research ,Molecular Medicine ,Fibroblast Growth Factor 2 ,Heparitin Sulfate ,Multiple Myeloma ,Signal Transduction - Abstract
Heparanase is a mammalian endoglycosidase that cleaves heparan sulfate (HS) polysaccharides and contributes to remodelling of the extracellular matrix and regulation of HS-binding protein bioavailabilities. Heparanase is upregulated in malignant cancers and inflammation, aiding cell migration and the release of signaling molecules. It is established as a highly druggable extracellular target for anticancer therapy, but current compounds have limitations, because of cost, production complexity, or off-target effects. Here, we report the synthesis of a novel, targeted library of single-entity glycomimetic clusters capped with simple sulfated saccharides. Several dendrimer HS glycomimetics display low nM IC 50 potency for heparanase inhibition equivalent to comparator compounds in clinical development, and potently inhibit metastasis and growth of human myeloma tumor cells in a mouse xenograft model. Importantly, they lack anticoagulant activity and cytotoxicity, and also inhibit angiogenesis. They provide a new candidate class for anticancer and wider therapeutic applications, which could benefit from targeted heparanase inhibition.
- Published
- 2018
47. Kinetic understanding of nitrogen supply condition on biosynthesis of polyhydroxyalkanoate from benzoate by Pseudomonas putida KT2440
- Author
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Bin Yang, Luis de la Torre, Aftab Ahamed, Arthur J. Ragauskas, Zhangyang Xu, Joshua S. Yuan, Chunmei Pan, Naijia Hao, Xiaolu Li, and John H. Miller
- Subjects
0106 biological sciences ,Environmental Engineering ,Nitrogen ,chemistry.chemical_element ,chemical and pharmacologic phenomena ,Bioengineering ,010501 environmental sciences ,01 natural sciences ,Benzoates ,Polyhydroxyalkanoates ,chemistry.chemical_compound ,Biosynthesis ,010608 biotechnology ,Lignin ,Food science ,Biomass ,Waste Management and Disposal ,0105 earth and related environmental sciences ,chemistry.chemical_classification ,biology ,Renewable Energy, Sustainability and the Environment ,Catabolism ,Pseudomonas putida ,Fatty Acids ,Fatty acid ,General Medicine ,biology.organism_classification ,Carbon ,Kinetics ,chemistry ,Bacteria - Abstract
Nitrogen supply is critical to the synthesis of intracellular PHA in various bacteria. However, the specific role of the nitrogen in synthesizing PHA from benzoate, a lignin model compound use for the study of bacteria catabolism of aromatics, is still not clear. In this study, two culture conditions were maintained for Pseudomonas putida KT2440 to produce PHA using benzoate as a carbon source. Under nitrogen-limited and surplus conditions, the accumulation of PHA was to 37.3% and 0.25% of cell dry weight, respectively. A model fit to the kinetics of biomass growth and PHA accumulation showed good agreement with data. GC–MS and NMR showed that PHA contained six hydroxyl fatty acid monomers under nitrogen-limited conditions, while two monomers were identified under nitrogen surplus conditions. The average molecular weight of PHA increased after the nitrogen source was exhausted. These results provide a promising strategy for optimization of lignin to PHA yields.
- Published
- 2018
48. Peloruside A Inhibits Growth of Human Lung and Breast Tumor Xenografts in an Athymic nu/nu Mouse Model
- Author
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Colin J. Meyer, Ginelle C. Gellert, Jef K. De Brabander, John H. Miller, Jerry W. Shay, Peter T. Northcote, Michael J. Wick, and Melissa Krauth
- Subjects
Cancer Research ,Lung Neoplasms ,Paclitaxel ,Mice, Nude ,Antineoplastic Agents ,Breast Neoplasms ,Docetaxel ,Pharmacology ,Inhibitory Concentration 50 ,Lactones ,Mice ,chemistry.chemical_compound ,In vivo ,Cell Line, Tumor ,medicine ,Animals ,Humans ,Doxorubicin ,Lung cancer ,Cell Proliferation ,Lung ,Cancer ,Bridged Bicyclo Compounds, Heterocyclic ,medicine.disease ,Xenograft Model Antitumor Assays ,Tumor Burden ,medicine.anatomical_structure ,Oncology ,chemistry ,Cell culture ,Female ,Taxoids ,medicine.drug - Abstract
Peloruside A is a microtubule-stabilizing agent isolated from a New Zealand marine sponge. Peloruside prevents growth of a panel of cancer cell lines at low nanomolar concentrations, including cell lines that are resistant to paclitaxel. Three xenograft studies in athymic nu/nu mice were performed to assess the efficacy of peloruside compared with standard anticancer agents such as paclitaxel, docetaxel, and doxorubicin. The first study examined the effect of 5 and 10 mg/kg peloruside (QD×5) on the growth of H460 non–small cell lung cancer xenografts. Peloruside caused tumor growth inhibition (%TGI) of 84% and 95%, respectively, whereas standard treatments with paclitaxel (8 mg/kg, QD×5) and docetaxel (6.3 mg/kg, Q2D×3) were much less effective (%TGI of 50% and 18%, respectively). In a second xenograft study using A549 lung cancer cells and varied schedules of dosing, activity of peloruside was again superior compared with the taxanes with inhibitions ranging from 51% to 74%, compared with 44% and 50% for the two taxanes. A third xenograft study in a P-glycoprotein–overexpressing NCI/ADR-RES breast tumor model showed that peloruside was better tolerated than either doxorubicin or paclitaxel. We conclude that peloruside is highly effective in preventing the growth of lung and P-glycoprotein–overexpressing breast tumors in vivo and that further therapeutic development is warranted. Mol Cancer Ther; 14(8); 1816–23. ©2015 AACR.
- Published
- 2015
49. The Nitrogenous Hamigerans: Unusual Amino Acid-Derivatized Aromatic Diterpenoid Metabolites from the New Zealand Marine Sponge Hamigera tarangaensis
- Author
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Jessica J. Field, Jonathan D. Dattelbaum, Peter T. Northcote, John H. Miller, and A. Jonathan Singh
- Subjects
chemistry.chemical_classification ,Dose-Response Relationship, Drug ,biology ,Chemistry ,Stereochemistry ,Organic Chemistry ,Molecular Conformation ,HL-60 Cells ,biology.organism_classification ,Molecular conformation ,Terpenoid ,Porifera ,Amino acid ,Adduct ,Structure-Activity Relationship ,Sponge ,Animals ,Humans ,Structure–activity relationship ,Organic chemistry ,Amino Acids ,Diterpenes ,Biogenesis ,Cell Proliferation ,New Zealand - Abstract
The NMR-directed isolation and structure elucidation of nine new nitrogenous hamigeran diterpenoids from the New Zealand marine sponge Hamigera tarangaensis are described. Featured in this set are the oxazole-containing hamigeran M (4) and eight compounds (5a-6a and 7a-8c) related to the constitutional structure of hamigeran D (1). Moderate cytotoxicity in the low-micromolar range against the HL-60 promyeloid leukemic cell line is reported for seven of the new compounds. The structural nature of these compounds suggests that their adducts are derived from an amino acid source and has allowed for revision of the configuration about C-18 of the archetypal compound, hamigeran D, from 1a to 1b. The existence of three constitutionally identical forms of hamigeran Q (8a-8c) requires the involvement of an allo-isoleucine stereoisomer and suggests the intriguing possibility of partial prokaryotic biogenesis of these unusual secondary metabolites.
- Published
- 2014
50. Developing nominal threshold levels for Phyllotreta cruciferae (Coleoptera: Chrysomelidae) damage on canola in Montana, USA
- Author
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Khanobporn Tangtrakulwanich, John H. Miller, Julie Prewett, Shaohui Wu, Victoria L. Ophus, and Gadi V. P. Reddy
- Subjects
Flea beetle ,Flea ,Leaf area damage ,food.ingredient ,biology ,Brassica napus ,Brassica ,Brassicaceae ,biology.organism_classification ,Crop ,chemistry.chemical_compound ,food ,Agronomy ,chemistry ,Imidacloprid ,Seed treatment ,Nominal thresholds ,Phyllotreta cruciferae ,Canola ,Agronomy and Crop Science - Abstract
The flea beetles Phyllotreta cruciferae (Goeze) and Phyllotreta striolata (F.) (Coleoptera: Chrysomelidae) are serious pests infesting canola (Brassica napus L.; Brassicales: Brassicaceae) in the Northern Great Plains of the United States. In Montana, P. cruciferae is the only flea beetle species that attacks canola during the crop growing stage. Management of P. cruciferae is usually focused on treating adults feeding on canola seedlings, which is the stage most vulnerable to flea beetle damage. In the Golden Triangle area in Montana, canola growers traditionally use seed treatments or calendar based spraying to control P. cruciferae. Here, we compared calendar-based spraying with seed treatment and threshold-based treatment. The experiment treatments included threshold levels (15e20, 25, 45% of leaf area damaged), calendar based sprays (15, 30 and 45 day intervals after plant emergence), seed treatments (imidacloprid), and untreated controls. The trials were done at two locations (Conrad and Western Triangle Agricultural Research Center). We found that calendar-based spraying at a 15-day interval did not differ significantly in yields from threshold-based treatment at 15e20% leaf damage. Also, the seed treatment did not give significantly higher yields compared to calendar-based sprays. A negative correlation was detected between leaf damage and yield in each treatment. Overall, calendar-based and threshold-based treatments were most effective in improving yields. However, treatment made at the threshold of 15e20% leaf area damage is recommended in order to reduce the number of chemical applications and also to reduce the possibility of selecting for resistance in flea beetles. © 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).
- Published
- 2014
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