1
|
Leung KK, Gerson J, Emmons N, Heemstra JM, Kippin TE, Plaxco KW. The Use of Xenonucleic Acids Significantly Reduces the In Vivo Drift of Electrochemical Aptamer-Based Sensors. Angew Chem Int Ed Engl 2024; 63:e202316678. [PMID: 38500260 DOI: 10.1002/anie.202316678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 02/09/2024] [Accepted: 03/17/2024] [Indexed: 03/20/2024]
Abstract
Electrochemical aptamer-based sensors support the high-frequency, real-time monitoring of molecules-of-interest in vivo. Achieving this requires methods for correcting the sensor drift seen during in vivo placements. While this correction ensures EAB sensor measurements remain accurate, as drift progresses it reduces the signal-to-noise ratio and precision. Here, we show that enzymatic cleavage of the sensor's target-recognizing DNA aptamer is a major source of this signal loss. To demonstrate this, we deployed a tobramycin-detecting EAB sensor analog fabricated with the DNase-resistant "xenonucleic acid" 2'O-methyl-RNA in a live rat. In contrast to the sensor employing the equivalent DNA aptamer, the 2'O-methyl-RNA aptamer sensor lost very little signal and had improved signal-to-noise. We further characterized the EAB sensor drift using unstructured DNA or 2'O-methyl-RNA oligonucleotides. While the two devices drift similarly in vitro in whole blood, the in vivo drift of the 2'O-methyl-RNA-employing device is less compared to the DNA-employing device. Studies of the electron transfer kinetics suggested that the greater drift of the latter sensor arises due to enzymatic DNA degradation. These findings, coupled with advances in the selection of aptamers employing XNA, suggest a means of improving EAB sensor stability when they are used to perform molecular monitoring in the living body.
Collapse
Affiliation(s)
- Kaylyn K Leung
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California, Santa Barbara
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Nicole Emmons
- Department of Psychological and Brain Sciences, University of California, Santa Barbara
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Jennifer M Heemstra
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Tod E Kippin
- Department of Psychological and Brain Sciences, University of California, Santa Barbara
- Department of Molecular Cellular and Developmental Biology, University of California, Santa Barbara
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| |
Collapse
|
2
|
Roehrich B, Leung KK, Gerson J, Kippin TE, Plaxco KW, Sepunaru L. Calibration-Free, Seconds-Resolved In Vivo Molecular Measurements using Fourier-Transform Impedance Spectroscopy Interrogation of Electrochemical Aptamer Sensors. ACS Sens 2023; 8:3051-3059. [PMID: 37584531 PMCID: PMC10463274 DOI: 10.1021/acssensors.3c00632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Accepted: 08/02/2023] [Indexed: 08/17/2023]
Abstract
Electrochemical aptamer-based (EAB) sensors are capable of measuring the concentrations of specific molecules in vivo, in real time, and with a few-second time resolution. For their signal transduction mechanism, these sensors utilize a binding-induced conformational change in their target-recognizing, redox-reporter-modified aptamer to alter the rate of electron transfer between the reporter and the supporting electrode. While a variety of voltammetric techniques have been used to monitor this change in kinetics, they suffer from various drawbacks, including time resolution limited to several seconds and sensor-to-sensor variation that requires calibration to remove. Here, however, we show that the use of fast Fourier transform electrochemical impedance spectroscopy (FFT-EIS) to interrogate EAB sensors leads to improved (here better than 2 s) time resolution and calibration-free operation, even when such sensors are deployed in vivo. To showcase these benefits, we demonstrate the approach's ability to perform real-time molecular measurements in the veins of living rats.
Collapse
Affiliation(s)
- Brian Roehrich
- Department
of Chemistry and Biochemistry, University
of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Kaylyn K. Leung
- Department
of Chemistry and Biochemistry, University
of California Santa Barbara, Santa Barbara, California 93106, United States
- Center
for Bioengineering, University of California
Santa Barbara, Santa Barbara, California 93106, United States
| | - Julian Gerson
- Department
of Psychological and Brain Sciences, University
of California, Santa Barbara, California 93106, United States
- Center
for Bioengineering, University of California
Santa Barbara, Santa Barbara, California 93106, United States
| | - Tod E. Kippin
- Department
of Psychological and Brain Sciences, University
of California, Santa Barbara, California 93106, United States
- Department
of Molecular Cellular and Developmental Biology, University of California, Santa
Barbara, California 93106,United States
| | - Kevin W. Plaxco
- Department
of Chemistry and Biochemistry, University
of California Santa Barbara, Santa Barbara, California 93106, United States
- Center
for Bioengineering, University of California
Santa Barbara, Santa Barbara, California 93106, United States
| | - Lior Sepunaru
- Department
of Chemistry and Biochemistry, University
of California Santa Barbara, Santa Barbara, California 93106, United States
| |
Collapse
|
3
|
Gerson J, Erdal MK, McDonough MH, Ploense KL, Dauphin-Ducharme P, Honeywell KM, Leung KK, Arroyo-Curras N, Gibson JM, Emmons NA, Meiring W, Hespanha JP, Plaxco KW, Kippin TE. High-precision monitoring of and feedback control over drug concentrations in the brains of freely moving rats. Sci Adv 2023; 9:eadg3254. [PMID: 37196087 PMCID: PMC10191434 DOI: 10.1126/sciadv.adg3254] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 04/12/2023] [Indexed: 05/19/2023]
Abstract
Knowledge of drug concentrations in the brains of behaving subjects remains constrained on a number of dimensions, including poor temporal resolution and lack of real-time data. Here, however, we demonstrate the ability of electrochemical aptamer-based sensors to support seconds-resolved, real-time measurements of drug concentrations in the brains of freely moving rats. Specifically, using such sensors, we achieve <4 μM limits of detection and 10-s resolution in the measurement of procaine in the brains of freely moving rats, permitting the determination of the pharmacokinetics and concentration-behavior relations of the drug with high precision for individual subjects. In parallel, we have used closed-loop feedback-controlled drug delivery to hold intracranial procaine levels constant (±10%) for >1.5 hours. These results demonstrate the utility of such sensors in (i) the determination of the site-specific, seconds-resolved neuropharmacokinetics, (ii) enabling the study of individual subject neuropharmacokinetics and concentration-response relations, and (iii) performing high-precision control over intracranial drug levels.
Collapse
Affiliation(s)
- Julian Gerson
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA
- Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA 93106, USA
| | - Murat Kaan Erdal
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA
| | - Matthew H. McDonough
- Department of Statistics and Applied Probability, University of California, Santa Barbara, CA 93106, USA
| | - Kyle L. Ploense
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA
| | | | - Kevin M. Honeywell
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA
| | - Kaylyn K. Leung
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA
| | - Netzahualcoyotl Arroyo-Curras
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jenny M. Gibson
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA
| | - Nicole A. Emmons
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA
| | - Wendy Meiring
- Department of Statistics and Applied Probability, University of California, Santa Barbara, CA 93106, USA
| | - Joao P. Hespanha
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA
| | - Kevin W. Plaxco
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA 93106, USA
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA
| | - Tod E. Kippin
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA
- Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
- Department of Molecular Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
| |
Collapse
|
4
|
Leung KK, Gerson J, Emmons N, Roehrich B, Verrinder E, Fetter LC, Kippin TE, Plaxco KW. A tight squeeze: geometric effects on the performance of three-electrode electrochemical-aptamer based sensors in constrained, in vivo placements. Analyst 2023; 148:1562-1569. [PMID: 36891771 DOI: 10.1039/d2an02096c] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
Electrochemical, aptamer-based (EAB) sensors are the first molecular monitoring technology that is (1) based on receptor binding and not the reactivity of the target, rendering it fairly general, and (2) able to support high-frequency, real-time measurements in situ in the living body. To date, EAB-derived in vivo measurements have largely been performed using three electrodes (working, reference, counter) bundled together within a catheter for insertion into the rat jugular. Exploring this architecture, here we show that the placement of these electrodes inside or outside of the lumen of the catheter significantly impacts sensor performance. Specifically, we find that retaining the counter electrode within the catheter increases the resistance between it and the working electrode, increasing the capacitive background. In contrast, extending the counter electrode outside the lumen of the catheter reduces this effect, significantly enhancing the signal-to-noise of intravenous molecular measurements. Exploring counter electrode geometries further, we find that they need not be larger than the working electrode. Putting these observations together, we have developed a new intravenous EAB architecture that achieves improved performance while remaining short enough to safely emplace in the rat jugular. These findings, though explored here with EAB sensors may prove important for the design of many electrochemical biosensors.
Collapse
Affiliation(s)
- Kaylyn K Leung
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA. .,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Nicole Emmons
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Brian Roehrich
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
| | - Elsi Verrinder
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA. .,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Lisa C Fetter
- Biomolecular Sciences and Engineering, University of California, Santa Barbara, California 93106, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Tod E Kippin
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA.,Department of Molecular Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA. .,Biomolecular Sciences and Engineering, University of California, Santa Barbara, California 93106, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| |
Collapse
|
5
|
Chamorro-Garcia A, Gerson J, Flatebo C, Fetter L, Downs AM, Emmons N, Ennis HL, Milosavić N, Yang K, Stojanovic M, Ricci F, Kippin TE, Plaxco KW. Real-Time, Seconds-Resolved Measurements of Plasma Methotrexate In Situ in the Living Body. ACS Sens 2023; 8:150-157. [PMID: 36534756 DOI: 10.1021/acssensors.2c01894] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Dose-limiting toxicity and significant patient-to-patient pharmacokinetic variability often render it difficult to achieve the safe and effective dosing of drugs. This is further compounded by the slow, cumbersome nature of the analytical methods used to monitor patient-specific pharmacokinetics, which inevitably rely on blood draws followed by post-facto laboratory analysis. Motivated by the pressing need for improved "therapeutic drug monitoring", we are developing electrochemical aptamer-based (EAB) sensors, a minimally invasive biosensor architecture that can provide real-time, seconds-resolved measurements of drug levels in situ in the living body. A key advantage of EAB sensors is that they are generalizable to the detection of a wide range of therapeutic agents because they are independent of the chemical or enzymatic reactivity of their targets. Three of the four therapeutic drug classes that have, to date, been shown measurable using in vivo EAB sensors, however, bind to nucleic acids as part of their mode of action, leaving open questions regarding the extent to which the approach can be generalized to therapeutics that do not. Here, we demonstrate real-time, in vivo measurements of plasma methotrexate, an antimetabolite (a mode of action not reliant on DNA binding) chemotherapeutic, following human-relevant dosing in a live rat animal model. By providing hundreds of drug concentration values, the resulting seconds-resolved measurements succeed in defining key pharmacokinetic parameters, including the drug's elimination rate, peak plasma concentration, and exposure (area under the curve), with unprecedented 5 to 10% precision. With this level of precision, we easily identify significant (>2-fold) differences in drug exposure occurring between even healthy rats given the same mass-adjusted methotrexate dose. By providing a real-time, seconds-resolved window into methotrexate pharmacokinetics, such measurements can be used to precisely "individualize" the dosing of this significantly toxic yet vitally important chemotherapeutic.
Collapse
Affiliation(s)
- Alejandro Chamorro-Garcia
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Dipartimento di Scienze e Tecnologie Chimiche, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Charlotte Flatebo
- Institute for Collaborative Biotechnologies, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Lisa Fetter
- Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Alex M Downs
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Nicole Emmons
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Herbert L Ennis
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University New York, New York, New York 10032, United States
| | - Nenad Milosavić
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University New York, New York, New York 10032, United States
| | - Kyungae Yang
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University New York, New York, New York 10032, United States
| | - Milan Stojanovic
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University New York, New York, New York 10032, United States.,Department of Biomedical Engineering and Systems Biology, Columbia University New York, New York, New York 10032, United States
| | - Francesco Ricci
- Dipartimento di Scienze e Tecnologie Chimiche, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Tod E Kippin
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Biological Engineering Graduate Program, University of California Santa Barbara, Santa Barbara, California 93106, United States
| |
Collapse
|
6
|
Presenter RRBN, Shah N, Alencar A, Gerson J, Patel M, Jurczak W, Patel K, Mato A, Cheah C, Wang M. PIRTOBRUTINIB, A HIGHLY SELECTIVE, NON-COVALENT (REVERSIBLE) BTK INHIBITOR IN PREVIOUSLY TREATED MANTLE CELL LYMPHOMA: UPDATED RESULTS FROM THE PHASE 1/2 BRUIN STUDY. Hematol Transfus Cell Ther 2022. [DOI: 10.1016/j.htct.2022.09.214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
7
|
Downs AM, Gerson J, Leung KK, Honeywell KM, Kippin T, Plaxco KW. Improved calibration of electrochemical aptamer-based sensors. Sci Rep 2022; 12:5535. [PMID: 35365672 PMCID: PMC8976050 DOI: 10.1038/s41598-022-09070-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 02/24/2022] [Indexed: 12/22/2022] Open
Abstract
Electrochemical aptamer-based (EAB) sensors support the real-time, high frequency measurement of pharmaceuticals and metabolites in-situ in the living body, rendering them a potentially powerful technology for both research and clinical applications. Here we explore quantification using EAB sensors, examining the impact of media selection and temperature on measurement performance. Using freshly-collected, undiluted whole blood at body temperature as both our calibration and measurement conditions, we demonstrate accuracy of better than ± 10% for the measurement of our test bed drug, vancomycin. Comparing titrations collected at room and body temperature, we find that matching the temperature of calibration curve collection to the temperature used during measurements improves quantification by reducing differences in sensor gain and binding curve midpoint. We likewise find that, because blood age impacts the sensor response, calibrating in freshly collected blood can improve quantification. Finally, we demonstrate the use of non-blood proxy media to achieve calibration without the need to collect fresh whole blood.
Collapse
Affiliation(s)
- Alex M Downs
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Kaylyn K Leung
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.,Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Kevin M Honeywell
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Tod Kippin
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.,The Neuroscience Research Institute and Department of Molecular Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Kevin W Plaxco
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA. .,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA. .,Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.
| |
Collapse
|
8
|
Downs AM, Gerson J, Hossain MN, Ploense K, Pham M, Kraatz HB, Kippin T, Plaxco KW. Nanoporous Gold for the Miniaturization of In Vivo Electrochemical Aptamer-Based Sensors. ACS Sens 2021; 6:2299-2306. [PMID: 34038076 DOI: 10.1021/acssensors.1c00354] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Electrochemical aptamer-based sensors enable real-time molecular measurements in the living body. The spatial resolution of these measurements and ability to perform measurements in targeted locations, however, is limited by the length and width of the device's working electrode. Historically, achieving good signal to noise in the complex, noisy in vivo environment has required working electrode lengths of 3-6 mm. To enable sensor miniaturization, here we have enhanced the signaling current obtained for a sensor of given macroscopic dimensions by increasing its surface area. Specifically, we produced nanoporous gold via an electrochemical alloying/dealloying technique to increase the microscopic surface area of our working electrodes by up to 100-fold. Using this approach, we have miniaturized in vivo electrochemical aptamer-based (EAB) sensors (here using sensors against the antibiotic, vancomycin) by a factor of 6 while retaining sensor signal and response times. Conveniently, the fabrication of nanoporous gold is simple, parallelizable, and compatible with both two- and three-dimensional electrode architectures, suggesting that it may be of value to a range of electrochemical biosensor applications.
Collapse
Affiliation(s)
- Alex M. Downs
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - M. Nur Hossain
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | - Kyle Ploense
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Michael Pham
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Heinz-Bernhard Kraatz
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Tod Kippin
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
- The Neuroscience Research Institute and Department of Molecular Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Kevin W. Plaxco
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| |
Collapse
|
9
|
Gerson J, Erdal M, Plaxco K, Kippin T, Hespanha J. Vein‐to‐brain: Simultaneous, seconds‐resolved measurements of intracranial and intravenous drug levels provide a highly time‐resolved picture of drug transport. FASEB J 2021. [DOI: 10.1096/fasebj.2021.35.s1.04095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Julian Gerson
- Psychological & Brain SciencesUniversity of California, Santa BarbaraSanta BarabaraCA
| | - Murat Erdal
- Electrical and Computer EngineeringUniversity of California, Santa BarbaraSanta BarabaraCA
| | - Kevin Plaxco
- Chemistry & BiochemistryUniversity of California, Santa BarbaraSanta BarabaraCA
| | - Tod Kippin
- University of California, Santa BarbaraSanta BarabaraCA
| | - Joao Hespanha
- Electrical and Computer EngineeringUniversity of California, Santa BarbaraSanta BarabaraCA
| |
Collapse
|
10
|
Downs AM, Gerson J, Ploense KL, Plaxco KW, Dauphin-Ducharme P. Subsecond-Resolved Molecular Measurements Using Electrochemical Phase Interrogation of Aptamer-Based Sensors. Anal Chem 2020; 92:14063-14068. [PMID: 32959647 DOI: 10.1021/acs.analchem.0c03109] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Recent years have seen the development of a number of biosensor architectures that rely on target binding-induced changes in the rate of electron transfer from an electrode-bound receptor. Most often, the interrogation of these sensors has relied on voltammetric methods, such as square-wave voltammetry, which limit their time resolution to a few seconds. Here, we describe the use of an impedance-based approach, which we have termed electrochemical phase interrogation, as a means of collecting high time resolution measurements with sensors in this class. Specifically, using changes in the electrochemical phase to monitor target binding in an electrochemical-aptamer based (EAB) sensor, we achieve subsecond temporal resolution and multihour stability in measurements performed directly in undiluted whole blood. Electrochemical phase interrogation also offers improved insights into EAB sensors' signaling mechanism. By modeling the interfacial resistance and capacitance using equivalent circuits, we find that the only parameter that is altered by target binding is the charge-transfer resistance. This confirms previous claims that binding-induced changes in electron-transfer kinetics drive signaling in this class of sensors. Considering that a wide range of electrochemical biosensor architectures rely on this signaling mechanism, we believe that electrochemical phase interrogation may prove generalizable toward subsecond measurements of molecular targets.
Collapse
Affiliation(s)
- Alex M Downs
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Kyle L Ploense
- Institute for Behavioral Genetics, University of Colorado, Boulder, Colorado 80309, United States
| | - Kevin W Plaxco
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | | |
Collapse
|
11
|
Dauphin-Ducharme P, Yang K, Arroyo-Currás N, Ploense KL, Zhang Y, Gerson J, Kurnik M, Kippin TE, Stojanovic MN, Plaxco KW. Electrochemical Aptamer-Based Sensors for Improved Therapeutic Drug Monitoring and High-Precision, Feedback-Controlled Drug Delivery. ACS Sens 2019; 4:2832-2837. [PMID: 31556293 PMCID: PMC6886665 DOI: 10.1021/acssensors.9b01616] [Citation(s) in RCA: 113] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The electrochemical aptamer-based (E-AB) sensing platform appears to be a convenient (rapid, single-step, and calibration-free) and modular approach to measure concentrations of specific molecules (irrespective of their chemical reactivity) directly in blood and even in situ in the living body. Given these attributes, the platform may thus provide significant opportunities to render therapeutic drug monitoring (the clinical practice in which dosing is adjusted in response to plasma drug measurements) as frequent and convenient as the measurement of blood sugar has become for diabetics. The ability to measure arbitrary molecules in the body in real time could even enable closed-loop feedback control over plasma drug levels in a manner analogous to the recently commercialized controlled blood sugar systems. As initial exploration of this, we describe here the selection of an aptamer against vancomycin, a narrow therapeutic window antibiotic for which therapeutic monitoring is a critical part of the standard of care, and its adaptation into an electrochemical aptamer-based (E-AB) sensor. Using this sensor, we then demonstrate: (i) rapid (seconds) and convenient (single-step and calibration-free) measurement of plasma vancomycin in finger-prick-scale samples of whole blood, (ii) high-precision measurement of subject-specific vancomycin pharmacokinetics (in a rat animal model), and (iii) high-precision, closed-loop feedback control over plasma levels of the drug (in a rat animal model). The ability to not only track (with continuous-glucose-monitor-like measurement frequency and convenience) but also actively control plasma drug levels provides an unprecedented route toward improving therapeutic drug monitoring and, more generally, the personalized, high-precision delivery of pharmacological interventions.
Collapse
Affiliation(s)
- Philippe Dauphin-Ducharme
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Kyungae Yang
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University, New York, New York 10032, United States
| | - Netzahualcóyotl Arroyo-Currás
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States
| | - Kyle L. Ploense
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Yameng Zhang
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University, New York, New York 10032, United States
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Martin Kurnik
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Tod E. Kippin
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Milan N. Stojanovic
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University, New York, New York 10032, United States
- Department of Biomedical Engineering and Systems Biology, Columbia University, New York, New York 10032, United States
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| |
Collapse
|
12
|
Svoboda J, Barta S, Nasta S, Landsburg D, Gerson J, Ruella M, Waite T, King C, Emanuel S, Ballard H, Schuster S. EVITA: PHASE I/II STUDY OF EVEROLIMUS PLUS ITACITINIB IN RELAPSED/REFRACTORY CLASSICAL HODGKIN LYMPHOMA. Hematol Oncol 2019. [DOI: 10.1002/hon.22_2632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- J. Svoboda
- Lymphoma Program; University of Pennsylvania; Philadelphia United States
| | - S. Barta
- Lymphoma Program; University of Pennsylvania; Philadelphia United States
| | - S. Nasta
- Lymphoma Program; University of Pennsylvania; Philadelphia United States
| | - D. Landsburg
- Lymphoma Program; University of Pennsylvania; Philadelphia United States
| | - J. Gerson
- Lymphoma Program; University of Pennsylvania; Philadelphia United States
| | - M. Ruella
- Lymphoma Program; University of Pennsylvania; Philadelphia United States
| | - T. Waite
- Lymphoma Program; University of Pennsylvania; Philadelphia United States
| | - C. King
- Lymphoma Program; University of Pennsylvania; Philadelphia United States
| | - S.A. Emanuel
- Lymphoma Program; University of Pennsylvania; Philadelphia United States
| | - H. Ballard
- Lymphoma Program; University of Pennsylvania; Philadelphia United States
| | - S. Schuster
- Lymphoma Program; University of Pennsylvania; Philadelphia United States
| |
Collapse
|
13
|
Bond D, Switchenko J, Maddocks K, Churnetski M, Goyal S, Shanmugasundaram K, Calzada O, Kolla B, Bachanova V, Gerson J, Barta S, Hill B, Salwaha Y, Martin P, Maldonado E, Gordon M, Danilov A, Grover N, Mathews S, Burkart M, Karmali R, Ghosh N, Park S, Epperla N, Badar T, Guo J, Hamadani M, Fenske T, Malecek M, Kahl B, Flowers C, Blum K, Cohen J. OUTCOMES FOR PATIENTS WITH MANTLE CELL LYMPHOMA EXPERIENCING FRONTLINE TREATMENT FAILURE: A MULTICENTER RETROSPECTIVE STUDY. Hematol Oncol 2019. [DOI: 10.1002/hon.77_2631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- D.A. Bond
- Division of Hematology; Ohio State University Comprehensive Cancer Center; Columbus United States
| | - J. Switchenko
- Department of Biostatistics and Bioinformatics; Rollins School of Public Health, Emory University; Atlanta United States
| | - K. Maddocks
- Division of Hematology; Ohio State University Comprehensive Cancer Center; Columbus United States
| | - M. Churnetski
- Department of Hematology and Medical Oncology; Winship Cancer Institute; Atlanta United States
| | - S. Goyal
- Department of Biostatistics and Bioinformatics; Rollins School of Public Health, Emory University; Atlanta United States
| | - K. Shanmugasundaram
- Department of Internal Medicine; Emory University School of Medicine; Atlanta United States
| | - O. Calzada
- Department of Hematology and Medical Oncology; Winship Cancer Institute; Atlanta United States
| | - B. Kolla
- Department of Hematology; University of Minnesota; Minneapolis United States
| | - V. Bachanova
- Department of Hematology; University of Minnesota; Minneapolis United States
| | - J. Gerson
- Hematology; Abramson Cancer Center, University of Pennsylvania; Pennsylvania United States
| | - S. Barta
- Hematology; Abramson Cancer Center, University of Pennsylvania; Pennsylvania United States
| | - B. Hill
- Hematology and Oncology; Cleveland Clinic Taussig Cancer Institute; Cleveland United States
| | - Y. Salwaha
- Hematology and Oncology; Cleveland Clinic Taussig Cancer Institute; Cleveland United States
| | - P. Martin
- Department of Medicine; Weil Cornell Medicine; New York United States
| | - E. Maldonado
- Hematology and Oncology; Oregon Health and Science University, Knight Cancer Institute; Portland United States
| | - M. Gordon
- Hematology and Oncology; Oregon Health and Science University, Knight Cancer Institute; Portland United States
| | - A. Danilov
- Hematology and Oncology; Oregon Health and Science University, Knight Cancer Institute; Portland United States
| | - N. Grover
- Hematology and Oncology; University of North Carolina Lineberger Comprehensive Cancer Center; Chapel Hill United States
| | - S. Mathews
- Hematology and Oncology; University of North Carolina Lineberger Comprehensive Cancer Center; Chapel Hill United States
| | - M. Burkart
- Hematology and Oncology; Northwestern University, Feinberg School of Medicine; Chicago United States
| | - R. Karmali
- Hematology and Oncology; Northwestern University, Feinberg School of Medicine; Chicago United States
| | - N. Ghosh
- Hematology and Oncology; Atrium Health; Charlotte United States
| | - S. Park
- Hematology and Oncology; Atrium Health; Charlotte United States
| | - N. Epperla
- Division of Hematology; Ohio State University Comprehensive Cancer Center; Columbus United States
| | - T. Badar
- Hematology and Oncology; Medical College of Wisconsin; Milwaukee United States
| | - J. Guo
- Department of Medicine; Weil Cornell Medicine; New York United States
| | - M. Hamadani
- Hematology and Oncology; Medical College of Wisconsin; Milwaukee United States
| | - T. Fenske
- Hematology and Oncology; Medical College of Wisconsin; Milwaukee United States
| | - M. Malecek
- Hematology and Oncology; Siteman Cancer Center, Washington University; St. Louis United States
| | - B. Kahl
- Hematology and Oncology; Siteman Cancer Center, Washington University; St. Louis United States
| | - C. Flowers
- Department of Hematology and Medical Oncology; Winship Cancer Institute; Atlanta United States
| | - K. Blum
- Department of Hematology and Medical Oncology; Winship Cancer Institute; Atlanta United States
| | - J. Cohen
- Department of Hematology and Medical Oncology; Winship Cancer Institute; Atlanta United States
| |
Collapse
|
14
|
Idili A, Gerson J, Parolo C, Kippin T, Plaxco KW. An electrochemical aptamer-based sensor for the rapid and convenient measurement of L-tryptophan. Anal Bioanal Chem 2019; 411:4629-4635. [PMID: 30796485 DOI: 10.1007/s00216-019-01645-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 01/09/2019] [Accepted: 01/24/2019] [Indexed: 01/01/2023]
Abstract
The field of precision medicine-the possibility to accurately tailor pharmacological treatments to each specific patient-would be significantly advanced by the ability to rapidly, conveniently, and cost-effectively measure biomarkers directly at the point of care. Electrochemical aptamer-based (E-AB) sensors appear a promising approach to this end due to their low cost, ease of use, and good analytical performance in complex clinical samples. Thus motivated, we present here the development of an E-AB sensor for the measurement of the amino acid L-tryptophan, a diagnostic marker indicative of a number of metabolic and mental health disorders, in urine. The sensor employs a previously reported DNA aptamer able to recognize the complex formed between tryptophan and a rhodium-based receptor. We adopted the aptamer to the E-AB sensing platform by truncating it, causing it to undergo a binding-induced conformational change, modifying it with a redox-reporting methylene blue, and attaching it to an interrogating electrode. The resulting sensor is able to measure tryptophan concentrations in the micromolar range in minutes and readily discriminates between its target and other aromatic and non-aromatic amino acids. Using it, we demonstrate the measurement of clinically relevant tryptophan levels in synthetic urine in a process requiring only a single dilution step. The speed and convenience with which this is achieved suggest that the E-AB platform could significantly improve the ease and frequency with which metabolic diseases are monitored. Graphical Abstract.
Collapse
Affiliation(s)
- Andrea Idili
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.,Center for Bioengineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Claudio Parolo
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.,Center for Bioengineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Tod Kippin
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.,Department of Molecular Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.,Department of Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA. .,Center for Bioengineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
| |
Collapse
|
15
|
Rakez K, Sengupta U, Gerson J, Hasan T, Carretero Murillo M, Castillo-Carranza D. Potential role of oligomeric tau stains in the pathogenesis of synucleinopathies. J Neurol Sci 2017. [DOI: 10.1016/j.jns.2017.08.285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
16
|
Thompson AB, Gerson J, Stolyarova A, Bugarin A, Hart EE, Jentsch JD, Izquierdo A. Steep effort discounting of a preferred reward over a freely-available option in prolonged methamphetamine withdrawal in male rats. Psychopharmacology (Berl) 2017; 234:2697-2705. [PMID: 28584929 PMCID: PMC6441328 DOI: 10.1007/s00213-017-4656-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 05/23/2017] [Indexed: 11/29/2022]
Abstract
RATIONALE Drug addiction can be described as aberrant allocation of effort toward acquiring drug, despite associated costs. It is unclear if this behavioral pattern results from an overvaluation of reward or to an altered sensitivity to costs. OBJECTIVE Present experiments assessed reward sensitivity and effortful choice in rats following 1 week of withdrawal from methamphetamine (mAMPH). METHODS Rats were treated with either saline or an escalating dose mAMPH regimen, then tested after a week without the drug. In experiment 1, rats were given a free choice between water and various concentrations of sucrose solution to assess general reward sensitivity. In experiment 2, rats were presented with a choice between lever-pressing for sucrose pellets on a progressive ratio schedule or consuming freely-available chow. RESULTS In experiment 1, we found no differences in sucrose preference between mAMPH- and saline-pretreated rats. In experiment 2, when selecting between two options, mAMPH-pretreated rats engaged in less lever-pressing for sucrose pellets (p < 0.01) and switched from this preferred reward to the chow sooner than saline-pretreated rats (p < 0.05). This effect was not consistent with general reward devaluation or loss of motivation. CONCLUSIONS These findings demonstrate that mAMPH exposure and withdrawal lead to steeper discounting of reward value by effort, an effect that is consistent with the effect of mAMPH on discounting by delay, and which may reflect an underlying shared mechanism.
Collapse
Affiliation(s)
- Andrew B. Thompson
- Department of Psychology, The Brain Research Institute, UCLA, Los Angeles, CA, USA
| | - Julian Gerson
- Department of Psychology, The Brain Research Institute, UCLA, Los Angeles, CA, USA
| | - Alexandra Stolyarova
- Department of Psychology, The Brain Research Institute, UCLA, Los Angeles, CA, USA
| | - Amador Bugarin
- Department of Psychology, The Brain Research Institute, UCLA, Los Angeles, CA, USA
| | - Evan E. Hart
- Department of Psychology, The Brain Research Institute, UCLA, Los Angeles, CA, USA
| | - J. David Jentsch
- Department of Psychology, The Brain Research Institute, UCLA, Los Angeles, CA, USA,Department of Psychology, The State University of New York, Binghamton University, Binghamton, NY, USA,Integrative Center for Learning and Memory, UCLA, Los Angeles, CA, USA,Integrative Center for Addictions, UCLA, Los Angeles, CA, USA
| | - Alicia Izquierdo
- Department of Psychology, The Brain Research Institute, UCLA, Los Angeles, CA, USA. .,Integrative Center for Learning and Memory, UCLA, Los Angeles, CA, USA. .,Integrative Center for Addictions, UCLA, Los Angeles, CA, USA.
| |
Collapse
|
17
|
Gerson J, Castillo-Carranza D, Sengupta U, Henson N, Nilson A, Kayed R. Tau oligomer antibodies as potential therapeutics for parkinson’s and other synucleinopathies. J Neurol Sci 2015. [DOI: 10.1016/j.jns.2015.08.110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
18
|
MacKay S, Ezekiel F, Di Sclafani V, Meyerhoff DJ, Gerson J, Norman D, Fein G, Weiner MW. Alzheimer disease and subcortical ischemic vascular dementia: evaluation by combining MR imaging segmentation and H-1 MR spectroscopic imaging. Radiology 1996; 198:537-45. [PMID: 8596863 PMCID: PMC2733362 DOI: 10.1148/radiology.198.2.8596863] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
PURPOSE To determine the association between H-1 magnetic resonance (MR) spectroscopic imaging and MR imaging differences in subjects with Alzheimer disease (AD) or subcortical ischemic vascular dementia (SIVD) versus control subjects and if both studies combined enable discrimination of AD from control subjects better than either study alone. MATERIALS AND METHODS Measures were obtained in nine AD, eight SIVD, and 11 control subjects with MR imaging segmentation software. RESULTS Statistically significantly lower N-acetylaspartate/choline-containing metabolites (Cho) and higher Cho/creatine-containing metabolites in posterior mesial gray matter in AD versus control subjects were independent of MR imagining differences. Combined measures allowed correct classification of AD and control subjects, but none of the MR measures allowed accurate discrimination between AD and SIVD subjects. CONCLUSION Between-group differences in tissue-type contributions to H-1 MR spectroscopic imaging voxels must be accounted for when reporting H-1 MR spectroscopic imaging data in AD, SIVD, and control subjects. Combined studies allowed more accurate discrimination between AD and control subjects than either study alone.
Collapse
Affiliation(s)
- S MacKay
- Department of Veterans Affairs (DVA) Medical Center, Magnetic Resonance Spectroscopy Unit, San Francisco, CA 94121, USA
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Constans JM, Meyerhoff DJ, Gerson J, MacKay S, Norman D, Fein G, Weiner MW. H-1 MR spectroscopic imaging of white matter signal hyperintensities: Alzheimer disease and ischemic vascular dementia. Radiology 1995; 197:517-23. [PMID: 7480705 PMCID: PMC2780019 DOI: 10.1148/radiology.197.2.7480705] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
PURPOSE To investigate the association of white matter signal hyperintensities (WMSHs) with changes in hydrogen-1 metabolites. MATERIALS AND METHODS T2-weighted magnetic resonance (MR) imaging and H-1 MR spectroscopic imaging were performed in 21 elderly control subjects without or with minimal WMSHs, eight elderly subjects with substantial WMSHs, 11 probable Alzheimer disease patients with WMSHs, and eight ischemic vascular dementia (IVD) patients with WMSHs. N-acetylaspartate (NAA), choline-containing metabolites (Cho), and creatine-containing metabolites (Cr) were analyzed. RESULTS Differences in regional metabolite levels were found within the supraventricular brain of elderly control subjects. In Alzheimer disease patients, extensive WMSHs showed a lower percentage of NAA and a higher percentage of Cho compared with contralateral normal-appearing white matter (NAWM); in IVD patients, extensive and large WMSHs were associated with a higher percentage of Cho and a lower percentage of Cr compared with contralateral NAWM. CONCLUSION Regional metabolite variation and the presence of WMSHs are important covariants that must be accounted for in analysis of MR spectroscopic data.
Collapse
Key Words
- brain, atrophy, 10.83
- brain, diseases, 10.781
- brain, ischemia, 10.781
- brain, mr, 10.12145
- brain, white matter, 10.12145
- dementia, 10.781, 10.83
Collapse
Affiliation(s)
- J M Constans
- Magnetic Resonance Spectroscopy Unit, Department of Veterans Affairs Medical Center, San Francisco, CA 94121, USA
| | | | | | | | | | | | | |
Collapse
|
20
|
Abstract
Equivalent-electrical dipole source modeling of evoked potential signals requires complicated non-linear multivariate optimization. Newton and non-linear simplex optimization methods often converge to a local minimum, and their results are affected by the procedure's starting parameter estimates. This paper describes simulated annealing, a more robust and resistant global optimization method. As an illustrative example, both the simplex and simulated annealing algorithms were used for parameter estimation in modeling wave V of the brain-stem auditory evoked potential (BAEP) using a single decaying sinusoid dipole source. Data for a single subject from 3000 responses to stimuli on each of 2 days were recorded, with modeling performed on 1000 response subaverages. Each estimation problem was run with 5 different sets of starting parameters. Simulated annealing always converged to the global minimum regardless of the starting parameter estimates while simplex often converged to markedly different solutions for different starting parameter estimates. No association was apparent between the simplex's converging to a local minimum and the closeness of the starting estimates to the true parameter values. Implementation of simulated annealing is discussed in terms of cooling schedules and other procedure parameters.
Collapse
Affiliation(s)
- J Gerson
- University of California, San Francisco
| | | | | |
Collapse
|
21
|
Abstract
This paper considers one way that occupational health professionals can assess the force exerted by keyboard users and the possible relationship between that force and the key force-displacement relationship. First, three personal-computer keyboards with the standard QWERTY layouts were tested as described by the American National Standard for Human Factors Engineering of Visual Display workstations (ANSI/HFS 100-1988) to determine the peak forces, 0.47-0.89N; displacements prior to the "breakaway" force that acknowledges key registration, 2.0-2.5 mm; and total key travel, 3.3-4.3 mm. Second, keyboard reaction forces were recorded while 10 subjects typed 4 alphanumeric sentences on the keyboards. It was found that the peak forces corresponding to each keystroke were 2.5 to 3.9 times the required activation forces, indicating that the subjects consistently displaced the keys to their limits. The average of the peak forces for all keystrokes was lowest for the keyboard with the lowest required activation force. It was concluded that keyboard reaction forces can be used as an index of finger forces for keying tasks. Further studies are necessary to evaluate the relationship between keyboard reaction forces, fatigue, and chronic muscle, tendon, and nerve disorders.
Collapse
Affiliation(s)
- T J Armstrong
- Center for Ergonomics, University of Michigan, Ann Arbor 48109-2117
| | | | | | | | | |
Collapse
|
22
|
Abstract
Suppression of auditory P50 evoked potential amplitude to the second of a pair of clicks is potentially important in psychiatric research because it has been shown to be abnormal in both schizophrenics and their relatives. However, its clinical utility using the standard single-channel electroencephalographic (EEG) peak picking methodology is under question because of low test-retest reliability. Dipole Components Modeling of the P50 component was attempted as a method for increasing the reliability of the P50 suppression measure. It was hypothesized that this procedure might work because of pooling of noise from the two responses and because of the use of topographic information. Six replications of a P50 suppression paradigm in 12 subjects were analyzed. Reliability using peak picking was 0.27, and was significantly increased to 0.63 using dipole modeling. Dipole modeling was helpful not only for better modeling the P50 when it was present, but also for deciding that there was no P50 response in one subject.
Collapse
|
23
|
Eskenazi B, Fenster L, Hudes M, Wyrobek AJ, Katz DF, Gerson J, Rempel DM. A study of the effect of perchloroethylene exposure on the reproductive outcomes of wives of dry-cleaning workers. Am J Ind Med 1991; 20:593-600. [PMID: 1793102 DOI: 10.1002/ajim.4700200503] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The purpose of this investigation was to compare the reproductive outcomes of wives of men exposed to perchloroethylene in the dry-cleaning industry compared to those of wives of laundry workers. Seventeen female partners of dry cleaners and 32 partners of laundry workers were interviewed. The number of pregnancies and the standardized fertility ratios were similar between the two groups. Wives of dry cleaners did not have higher rates of spontaneous abortions. However, wives of dry cleaners were more than twice as likely to have a history of attempting to become pregnant for more than 12 months or to have sought care for an infertility problem. Cox proportional hazards models indicated that dry-cleaners' wives had half of the per-cycle pregnancy rate of wives of laundry workers, when controlling for other potential confounders (estimated rate ratio of 0.54, 95% C.I. = 0.23, 1.27).
Collapse
Affiliation(s)
- B Eskenazi
- Program of Maternal and Child Health, School of Public Health, University of California, Berkeley 94720
| | | | | | | | | | | | | |
Collapse
|
24
|
Gerson J, Varesio L, Herberman RB. Systemic and in situ natural killer and suppressor cell activities in mice bearing progressively growing murine sarcoma-virus-induced tumors. Int J Cancer 1981; 27:243-8. [PMID: 6457000 DOI: 10.1002/ijc.2910270218] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The activity of systemic and in situ natural killer (NK) cells was measured in 3- to 5-week-old CBA mice with progressively growing murine sarcoma virus (MSV)-induced tumors. Splenic NK activity was depressed in tumor-bearing mice. NK activity was quite low or not detectable in unfractionated cell suspensions from the tumors 10-12 days after inoculation of virus, but activity was observed upon depletion of phagocytic and/or adherent cells. To determine whether this in situ inhibition of NK activity was correlated with the presence of previously described suppressor cells, subpopulations of cells from the tumors were tested for their ability to suppress various responses of normal spleen cells: NK activity, lymphoproliferative responses to concanavalin A, and proliferation-independent production of macrophage inhibition factor. A similar pattern of suppressor activity was seen in all of the assays, indicating the presence of pleiotropic suppressor cells in progressively growing MSV-induced tumors.
Collapse
|
25
|
Herberman RB, Holden HT, Varesio L, Taniyama T, Puccetti P, Kirchner H, Gerson J, White S, Keisari Y, Haskill JS. Immunologic reactivity of lymphoid cells in tumors. Contemp Top Immunobiol 1980; 10:61-78. [PMID: 6967800 DOI: 10.1007/978-1-4684-3677-8_3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
|
26
|
Abstract
As part of a more extensive study of the immune response in children with neuroblastoma, serum immunoglobulin and alpha-glycoprotein levels were measured in 58 patients. Twenty-nine children were studied at diagnosis, 18 at some time during the first 2 years of treatment, and 11 who were apparently cured after treatment had been completed. No correlation was found between the levels of IgG, IgA, and IgM and the clinical status of the patient. The acute phase reactants (alpha-1-antitrypsin, haptoglobin, C3 component of complement and orosomucoid) varied with the disease status. Twenty-seven of the 29 patients had elevated levels at the time of diagnosis. Alpha-1-antitrypsin and haptoglobin were the two proteins that most accurately reflection the clinical status; C3 component of complement was not infrequently normal when the disease was active; and orosomucoid was sometimes raised in patients apparently in remission. Serial measurement of alpha-1-antitrypsin and haptoglobin could provide a useful means of detecting early relapse in patients responding to treatment.
Collapse
|
27
|
|
28
|
Evans AE, Gerson J, Schnaufer L. Spontaneous regression of neuroblastoma. Natl Cancer Inst Monogr 1976; 44:49-54. [PMID: 1030781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Case of spontaneous regression of neuroblastoma continue to occur in the present multimodal therapy era at institutions where physicians are prepared to withhold treatment on certain patients with residual primary or metastatic disease. From a survey of the 22 member institutions of Children's Cancer Study Group, seven hospitals submitted data on 24 neuroblastoma patients whose disease underwent regression after minimal, unusual, or no treatment. An analysis of these patients and of 33 patients form two large series in the literature shows that the majority of patients are infants with Stage II or Stage IVS disease. The spontaneous regression usually consists of complete disappearance of the disease, but in some neuroblastomas, maturation to ganglioneuroma takes place. The various factors that may influence regression are discussed.
Collapse
|
29
|
|