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Gogliettino AR, Cooler S, Vilkhu RS, Brackbill NJ, Rhoades C, Wu EG, Kling A, Sher A, Litke AM, Chichilnisky EJ. Modeling responses of macaque and human retinal ganglion cells to natural images using a convolutional neural network. bioRxiv 2024:2024.03.22.586353. [PMID: 38585930 PMCID: PMC10996505 DOI: 10.1101/2024.03.22.586353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Linear-nonlinear (LN) cascade models provide a simple way to capture retinal ganglion cell (RGC) responses to artificial stimuli such as white noise, but their ability to model responses to natural images is limited. Recently, convolutional neural network (CNN) models have been shown to produce light response predictions that were substantially more accurate than those of a LN model. However, this modeling approach has not yet been applied to responses of macaque or human RGCs to natural images. Here, we train and test a CNN model on responses to natural images of the four numerically dominant RGC types in the macaque and human retina - ON parasol, OFF parasol, ON midget and OFF midget cells. Compared with the LN model, the CNN model provided substantially more accurate response predictions. Linear reconstructions of the visual stimulus were more accurate for CNN compared to LN model-generated responses, relative to reconstructions obtained from the recorded data. These findings demonstrate the effectiveness of a CNN model in capturing light responses of major RGC types in the macaque and human retinas in natural conditions.
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Wu EG, Rudzite AM, Bohlen MO, Li PH, Kling A, Cooler S, Rhoades C, Brackbill N, Gogliettino AR, Shah NP, Madugula SS, Sher A, Litke AM, Field GD, Chichilnisky E. Decomposition of retinal ganglion cell electrical images for cell type and functional inference. bioRxiv 2023:2023.11.06.565889. [PMID: 37986895 PMCID: PMC10659265 DOI: 10.1101/2023.11.06.565889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Identifying neuronal cell types and their biophysical properties based on their extracellular electrical features is a major challenge for experimental neuroscience and the development of high-resolution brain-machine interfaces. One example is identification of retinal ganglion cell (RGC) types and their visual response properties, which is fundamental for developing future electronic implants that can restore vision. The electrical image (EI) of a RGC, or the mean spatio-temporal voltage footprint of its recorded spikes on a high-density electrode array, contains substantial information about its anatomical, morphological, and functional properties. However, the analysis of these properties is complex because of the high-dimensional nature of the EI. We present a novel optimization-based algorithm to decompose electrical image into a low-dimensional, biophysically-based representation: the temporally-shifted superposition of three learned basis waveforms corresponding to spike waveforms produced in the somatic, dendritic and axonal cellular compartments. Large-scale multi-electrode recordings from the macaque retina were used to test the effectiveness of the decomposition. The decomposition accurately localized the somatic and dendritic compartments of the cell. The imputed dendritic fields of RGCs correctly predicted the location and shape of their visual receptive fields. The inferred waveform amplitudes and shapes accurately identified the four major primate RGC types (ON and OFF midget and parasol cells), a substantial advance. Together, these findings may contribute to more accurate inference of RGC types and their original light responses in the degenerated retina, with possible implications for other electrical imaging applications.
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Affiliation(s)
- Eric G. Wu
- Department of Electrical Engineering, Stanford University
| | | | | | - Peter H. Li
- Department of Neurosurgery, Stanford University
- Department of Ophthalmology, Stanford University
- Hansen Experimental Physics Laboratory, Stanford University
| | - Alexandra Kling
- Department of Neurosurgery, Stanford University
- Department of Ophthalmology, Stanford University
- Hansen Experimental Physics Laboratory, Stanford University
| | - Sam Cooler
- Department of Neurosurgery, Stanford University
| | | | | | | | - Nishal P. Shah
- Department of Electrical Engineering, Stanford University
- Department of Neurosurgery, Stanford University
| | - Sasidhar S. Madugula
- Neurosciences PhD Program, Stanford University
- Stanford School of Medicine, Stanford University
| | - Alexander Sher
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz
| | - Alan M. Litke
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz
| | - Greg D. Field
- Department of Neurobiology, Duke University
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles
| | - E.J. Chichilnisky
- Department of Neurosurgery, Stanford University
- Department of Ophthalmology, Stanford University
- Hansen Experimental Physics Laboratory, Stanford University
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Wu EG, Brackbill N, Rhoades C, Kling A, Gogliettino AR, Shah NP, Sher A, Litke AM, Simoncelli EP, Chichilnisky E. Fixational Eye Movements Enhance the Precision of Visual Information Transmitted by the Primate Retina. bioRxiv 2023:2023.08.12.552902. [PMID: 37645934 PMCID: PMC10462030 DOI: 10.1101/2023.08.12.552902] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Fixational eye movements alter the number and timing of spikes transmitted from the retina to the brain, but whether these changes enhance or degrade the visual signal is unclear. To quantify this, we developed a Bayesian method for reconstructing natural images from the recorded spikes of hundreds of macaque retinal ganglion cells (RGCs) of the major cell types, combining a likelihood model for RGC light responses with the natural image prior implicitly embedded in an artificial neural network optimized for denoising. The method matched or surpassed the performance of previous reconstruction algorithms, and provided an interpretable framework for characterizing the retinal signal. Reconstructions were improved with artificial stimulus jitter that emulated fixational eye movements, even when the jitter trajectory was inferred from retinal spikes. Reconstructions were degraded by small artificial perturbations of spike times, revealing more precise temporal encoding than suggested by previous studies. Finally, reconstructions were substantially degraded when derived from a model that ignored cell-to-cell interactions, indicating the importance of stimulus-evoked correlations. Thus, fixational eye movements enhance the precision of the retinal representation.
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Affiliation(s)
- Eric G. Wu
- Department of Electrical Engineering, Stanford University
| | | | | | - Alexandra Kling
- Department of Neurosurgery, Stanford University
- Department of Ophthalmology, Stanford University
- Hansen Experimental Physics Laboratory, Stanford University
| | - Alex R. Gogliettino
- Hansen Experimental Physics Laboratory, Stanford University
- Neurosciences PhD Program, Stanford University
| | - Nishal P. Shah
- Department of Electrical Engineering, Stanford University
- Department of Neurosurgery, Stanford University
| | - Alexander Sher
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz
| | - Alan M. Litke
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz
| | - Eero P. Simoncelli
- Flatiron Institute, Simons Foundation
- Center for Neural Science, New York University
- Courant Institute of Mathematical Sciences, New York University
| | - E.J. Chichilnisky
- Department of Neurosurgery, Stanford University
- Department of Ophthalmology, Stanford University
- Hansen Experimental Physics Laboratory, Stanford University
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Zaidi M, Aggarwal G, Shah NP, Karniol-Tambour O, Goetz G, Madugula SS, Gogliettino AR, Wu EG, Kling A, Brackbill N, Sher A, Litke AM, Chichilnisky EJ. Inferring light responses of primate retinal ganglion cells using intrinsic electrical signatures. J Neural Eng 2023; 20:10.1088/1741-2552/ace657. [PMID: 37433293 PMCID: PMC11067857 DOI: 10.1088/1741-2552/ace657] [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: 07/15/2022] [Accepted: 07/11/2023] [Indexed: 07/13/2023]
Abstract
Objective. Retinal implants are designed to stimulate retinal ganglion cells (RGCs) in a way that restores sight to individuals blinded by photoreceptor degeneration. Reproducing high-acuity vision with these devices will likely require inferring the natural light responses of diverse RGC types in the implanted retina, without being able to measure them directly. Here we demonstrate an inference approach that exploits intrinsic electrophysiological features of primate RGCs.Approach.First, ON-parasol and OFF-parasol RGC types were identified using their intrinsic electrical features in large-scale multi-electrode recordings from macaque retina. Then, the electrically inferred somatic location, inferred cell type, and average linear-nonlinear-Poisson model parameters of each cell type were used to infer a light response model for each cell. The accuracy of the cell type classification and of reproducing measured light responses with the model were evaluated.Main results.A cell-type classifier trained on 246 large-scale multi-electrode recordings from 148 retinas achieved 95% mean accuracy on 29 test retinas. In five retinas tested, the inferred models achieved an average correlation with measured firing rates of 0.49 for white noise visual stimuli and 0.50 for natural scenes stimuli, compared to 0.65 and 0.58 respectively for models fitted to recorded light responses (an upper bound). Linear decoding of natural images from predicted RGC activity in one retina showed a mean correlation of 0.55 between decoded and true images, compared to an upper bound of 0.81 using models fitted to light response data.Significance.These results suggest that inference of RGC light response properties from intrinsic features of their electrical activity may be a useful approach for high-fidelity sight restoration. The overall strategy of first inferring cell type from electrical features and then exploiting cell type to help infer natural cell function may also prove broadly useful to neural interfaces.
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Affiliation(s)
- Moosa Zaidi
- Stanford University School of Medicine, Stanford University, Stanford, CA, United States of America
- Neurosurgery, Stanford University, Stanford, CA, United States of America
| | - Gorish Aggarwal
- Neurosurgery, Stanford University, Stanford, CA, United States of America
- Electrical Engineering, Stanford University, Stanford, CA, United States of America
| | - Nishal P Shah
- Neurosurgery, Stanford University, Stanford, CA, United States of America
| | - Orren Karniol-Tambour
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, United States of America
| | - Georges Goetz
- Neurosurgery, Stanford University, Stanford, CA, United States of America
| | - Sasidhar S Madugula
- Stanford University School of Medicine, Stanford University, Stanford, CA, United States of America
- Neurosciences, Stanford University, Stanford, CA, United States of America
| | - Alex R Gogliettino
- Neurosciences, Stanford University, Stanford, CA, United States of America
| | - Eric G Wu
- Electrical Engineering, Stanford University, Stanford, CA, United States of America
| | - Alexandra Kling
- Neurosurgery, Stanford University, Stanford, CA, United States of America
| | - Nora Brackbill
- Physics, Stanford University, Stanford, CA, United States of America
| | - Alexander Sher
- Santa Cruz Institute for Particle Physics, University of California Santa Cruz, Santa Cruz, CA, United States of America
| | - Alan M Litke
- Santa Cruz Institute for Particle Physics, University of California Santa Cruz, Santa Cruz, CA, United States of America
| | - E J Chichilnisky
- Neurosurgery, Stanford University, Stanford, CA, United States of America
- Ophthalmology, Stanford University, Stanford, CA, United States of America
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Madugula SS, Vilkhu R, Shah NP, Grosberg LE, Kling A, Gogliettino AR, Nguyen H, Hottowy P, Sher A, Litke AM, Chichilnisky EJ. Inference of Electrical Stimulation Sensitivity from Recorded Activity of Primate Retinal Ganglion Cells. J Neurosci 2023; 43:4808-4820. [PMID: 37268418 PMCID: PMC10312054 DOI: 10.1523/jneurosci.1023-22.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [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: 05/27/2022] [Revised: 05/22/2023] [Accepted: 05/24/2023] [Indexed: 06/04/2023] Open
Abstract
High-fidelity electronic implants can in principle restore the function of neural circuits by precisely activating neurons via extracellular stimulation. However, direct characterization of the individual electrical sensitivity of a large population of target neurons, to precisely control their activity, can be difficult or impossible. A potential solution is to leverage biophysical principles to infer sensitivity to electrical stimulation from features of spontaneous electrical activity, which can be recorded relatively easily. Here, this approach is developed and its potential value for vision restoration is tested quantitatively using large-scale multielectrode stimulation and recording from retinal ganglion cells (RGCs) of male and female macaque monkeys ex vivo Electrodes recording larger spikes from a given cell exhibited lower stimulation thresholds across cell types, retinas, and eccentricities, with systematic and distinct trends for somas and axons. Thresholds for somatic stimulation increased with distance from the axon initial segment. The dependence of spike probability on injected current was inversely related to threshold, and was substantially steeper for axonal than somatic compartments, which could be identified by their recorded electrical signatures. Dendritic stimulation was largely ineffective for eliciting spikes. These trends were quantitatively reproduced with biophysical simulations. Results from human RGCs were broadly similar. The inference of stimulation sensitivity from recorded electrical features was tested in a data-driven simulation of visual reconstruction, revealing that the approach could significantly improve the function of future high-fidelity retinal implants.SIGNIFICANCE STATEMENT This study demonstrates that individual in situ primate retinal ganglion cells of different types respond to artificially generated, external electrical fields in a systematic manner, in accordance with theoretical predictions, that allows for prediction of electrical stimulus sensitivity from recorded spontaneous activity. It also provides evidence that such an approach could be immensely helpful in the calibration of clinical retinal implants.
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Affiliation(s)
- Sasidhar S Madugula
- Neurosciences PhD Program, Stanford University, Stanford, California 94305
- School of Medicine, Stanford University, Stanford, California 94305
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
| | - Ramandeep Vilkhu
- Department of Electrical Engineering, Stanford University, Stanford, California 94305
| | - Nishal P Shah
- Department of Neurosurgery, Stanford University, Stanford, California 94305
- Department of Electrical Engineering, Stanford University, Stanford, California 94305
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
| | - Lauren E Grosberg
- Department of Neurosurgery, Stanford University, Stanford, California 94305
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
- Facebook Reality Labs, Facebook, Mountain View, California 94040
| | - Alexandra Kling
- Department of Neurosurgery, Stanford University, Stanford, California 94305
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
| | - Alex R Gogliettino
- Neurosciences PhD Program, Stanford University, Stanford, California 94305
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
| | - Huy Nguyen
- Department of Neurosurgery, Stanford University, Stanford, California 94305
| | - Paweł Hottowy
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Krakow, Poland 30-059
| | - Alexander Sher
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, California 95064
| | - Alan M Litke
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, California 95064
| | - E J Chichilnisky
- Department of Neurosurgery, Stanford University, Stanford, California 94305
- Department of Ophthalmology, Stanford University, Stanford, California 94305
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
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Gogliettino AR, Madugula SS, Grosberg LE, Vilkhu RS, Brown J, Nguyen H, Kling A, Hottowy P, Dąbrowski W, Sher A, Litke AM, Chichilnisky EJ. High-Fidelity Reproduction of Visual Signals by Electrical Stimulation in the Central Primate Retina. J Neurosci 2023; 43:4625-4641. [PMID: 37188516 PMCID: PMC10286946 DOI: 10.1523/jneurosci.1091-22.2023] [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: 05/31/2022] [Revised: 05/08/2023] [Accepted: 05/10/2023] [Indexed: 05/17/2023] Open
Abstract
Electrical stimulation of retinal ganglion cells (RGCs) with electronic implants provides rudimentary artificial vision to people blinded by retinal degeneration. However, current devices stimulate indiscriminately and therefore cannot reproduce the intricate neural code of the retina. Recent work has demonstrated more precise activation of RGCs using focal electrical stimulation with multielectrode arrays in the peripheral macaque retina, but it is unclear how effective this can be in the central retina, which is required for high-resolution vision. This work probes the neural code and effectiveness of focal epiretinal stimulation in the central macaque retina, using large-scale electrical recording and stimulation ex vivo The functional organization, light response properties, and electrical properties of the major RGC types in the central retina were mostly similar to the peripheral retina, with some notable differences in density, kinetics, linearity, spiking statistics, and correlations. The major RGC types could be distinguished by their intrinsic electrical properties. Electrical stimulation targeting parasol cells revealed similar activation thresholds and reduced axon bundle activation in the central retina, but lower stimulation selectivity. Quantitative evaluation of the potential for image reconstruction from electrically evoked parasol cell signals revealed higher overall expected image quality in the central retina. An exploration of inadvertent midget cell activation suggested that it could contribute high spatial frequency noise to the visual signal carried by parasol cells. These results support the possibility of reproducing high-acuity visual signals in the central retina with an epiretinal implant.SIGNIFICANCE STATEMENT Artificial restoration of vision with retinal implants is a major treatment for blindness. However, present-day implants do not provide high-resolution visual perception, in part because they do not reproduce the natural neural code of the retina. Here, we demonstrate the level of visual signal reproduction that is possible with a future implant by examining how accurately responses to electrical stimulation of parasol retinal ganglion cells can convey visual signals. Although the precision of electrical stimulation in the central retina was diminished relative to the peripheral retina, the quality of expected visual signal reconstruction in parasol cells was greater. These findings suggest that visual signals could be restored with high fidelity in the central retina using a future retinal implant.
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Affiliation(s)
- Alex R Gogliettino
- Neurosciences PhD Program, Stanford University, Stanford, California 94305
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
| | - Sasidhar S Madugula
- Neurosciences PhD Program, Stanford University, Stanford, California 94305
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
- Stanford School of Medicine, Stanford University, Stanford, California 94305
| | - Lauren E Grosberg
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
- Department of Neurosurgery, Stanford University, Stanford, California 94305
| | - Ramandeep S Vilkhu
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
- Department of Electrical Engineering, Stanford University, Stanford, California 94305
| | - Jeff Brown
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
- Department of Neurosurgery, Stanford University, Stanford, California 94305
- Department of Electrical Engineering, Stanford University, Stanford, California 94305
| | - Huy Nguyen
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
| | - Alexandra Kling
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
- Department of Neurosurgery, Stanford University, Stanford, California 94305
| | - Paweł Hottowy
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059, Kraków, Poland
| | - Władysław Dąbrowski
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059, Kraków, Poland
| | - Alexander Sher
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, Santa Cruz, California 95064
| | - Alan M Litke
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, Santa Cruz, California 95064
| | - E J Chichilnisky
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305
- Department of Neurosurgery, Stanford University, Stanford, California 94305
- Department of Electrical Engineering, Stanford University, Stanford, California 94305
- Department of Ophthalmology, Stanford University, Stanford, California 94305
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Wang P, Wu EG, Uluşan H, Phillips A, Rose Hays M, Kling A, Zhao ET, Madugula S, Vilkhu RS, Vasireddy PK, Hier- lemann A, Hong G, Chichilnisky E, Melosh NA. Direct-print three-dimensional electrodes for large- scale, high-density, and customizable neural inter- faces. bioRxiv 2023:2023.05.30.542925. [PMID: 37398164 PMCID: PMC10312573 DOI: 10.1101/2023.05.30.542925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Silicon-based planar microelectronics is a powerful tool for scalably recording and modulating neural activity at high spatiotemporal resolution, but it remains challenging to target neural structures in three dimensions (3D). We present a method for directly fabricating 3D arrays of tissue-penetrating microelectrodes onto silicon microelectronics. Leveraging a high-resolution 3D printing technology based on 2-photon polymerization and scalable microfabrication processes, we fabricated arrays of 6,600 microelectrodes 10-130 μm tall and at 35-μm pitch onto a planar silicon-based microelectrode array. The process enables customizable electrode shape, height and positioning for precise targeting of neuron populations distributed in 3D. As a proof of concept, we addressed the challenge of specifically targeting retinal ganglion cell (RGC) somas when interfacing with the retina. The array was customized for insertion into the retina and recording from somas while avoiding the axon layer. We verified locations of the microelectrodes with confocal microscopy and recorded high-resolution spontaneous RGC activity at cellular resolution. This revealed strong somatic and dendritic components with little axon contribution, unlike recordings with planar microelectrode arrays. The technology could be a versatile solution for interfacing silicon microelectronics with neural structures and modulating neural activity at large scale with single-cell resolution.
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Affiliation(s)
- Pingyu Wang
- Department of Materials Science and Engineering, Stanford University
| | - Eric G. Wu
- Department of Electrical Engineering, Stanford University, Stanford University
| | - Hasan Uluşan
- Department of Biosystems Science and Engineering in Basel, ETH Zürich
| | - A.J. Phillips
- Department of Electrical Engineering, Stanford University, Stanford University
| | | | | | - Eric T. Zhao
- Department of Chemical Engineering, Stanford University
| | | | - Ramandeep S. Vilkhu
- Department of Electrical Engineering, Stanford University, Stanford University
| | | | | | - Guosong Hong
- Department of Materials Science and Engineering, Stanford University
| | - E.J. Chichilnisky
- Department of Neurosurgery, Stanford University
- Hansen Experimental Physics Laboratory, Stanford University
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Madugula SS, Gogliettino AR, Zaidi M, Aggarwal G, Kling A, Shah NP, Brown JB, Vilkhu R, Hays MR, Nguyen H, Fan V, Wu EG, Hottowy P, Sher A, Litke AM, Silva RA, Chichilnisky EJ. Focal electrical stimulation of human retinal ganglion cells for vision restoration. J Neural Eng 2022; 19:066040. [PMID: 36533865 PMCID: PMC10010036 DOI: 10.1088/1741-2552/aca5b5] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [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: 07/18/2022] [Accepted: 11/24/2022] [Indexed: 11/25/2022]
Abstract
Objective. Vision restoration with retinal implants is limited by indiscriminate simultaneous activation of many cells and cell types, which is incompatible with reproducing the neural code of the retina. Recent work has shown that primate retinal ganglion cells (RGCs), which transmit visual information to the brain, can be directly electrically activated with single-cell, single-spike, cell-type precision - however, this possibility has never been tested in the human retina. In this study we aim to characterize, for the first time, direct in situ extracellular electrical stimulation of individual human RGCs.Approach. Extracellular electrical stimulation of individual human RGCs was conducted in three human retinas ex vivo using a custom large-scale, multi-electrode array capable of simultaneous recording and stimulation. Measured activation properties were compared directly to extensive results from macaque.Main results. Precise activation was in many cases possible without activating overlying axon bundles, at low stimulation current levels similar to those used in macaque. The major RGC types could be identified and targeted based on their distinctive electrical signatures. The measured electrical activation properties of RGCs, combined with a dynamic stimulation algorithm, was sufficient to produce an evoked visual signal that was nearly optimal given the constraints of the interface.Significance. These results suggest the possibility of high-fidelity vision restoration in humans using bi-directional epiretinal implants.
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Affiliation(s)
- Sasidhar S Madugula
- Neurosciences PhD Program, Stanford University, Stanford, CA, United States of America
- School of Medicine, Stanford University, Stanford, CA, United States of America
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
| | - Alex R Gogliettino
- Neurosciences PhD Program, Stanford University, Stanford, CA, United States of America
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
| | - Moosa Zaidi
- Department of Neurosurgery, Stanford University, Stanford, CA, United States of America
- School of Medicine, Stanford University, Stanford, CA, United States of America
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
| | - Gorish Aggarwal
- Department of Neurosurgery, Stanford University, Stanford, CA, United States of America
- Department of Electrical Engineering, Stanford University, Stanford, CA, United States of America
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
| | - Alexandra Kling
- Department of Neurosurgery, Stanford University, Stanford, CA, United States of America
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
| | - Nishal P Shah
- Department of Neurosurgery, Stanford University, Stanford, CA, United States of America
- Department of Electrical Engineering, Stanford University, Stanford, CA, United States of America
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
| | - Jeff B Brown
- Department of Electrical Engineering, Stanford University, Stanford, CA, United States of America
| | - Ramandeep Vilkhu
- Department of Electrical Engineering, Stanford University, Stanford, CA, United States of America
| | - Madeline R Hays
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
- Department of Bioengineering, Stanford University, Stanford, CA, United States of America
| | - Huy Nguyen
- Department of Neurosurgery, Stanford University, Stanford, CA, United States of America
| | - Victoria Fan
- Department of Neurosurgery, Stanford University, Stanford, CA, United States of America
| | - Eric G Wu
- Department of Electrical Engineering, Stanford University, Stanford, CA, United States of America
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
| | - Pawel Hottowy
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Krakow, Poland
| | - Alexander Sher
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, CA, United States of America
| | - Alan M Litke
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, CA, United States of America
| | - Ruwan A Silva
- Department of Ophthalmology, Stanford University, Stanford, CA, United States of America
| | - E J Chichilnisky
- Department of Neurosurgery, Stanford University, Stanford, CA, United States of America
- Department of Ophthalmology, Stanford University, Stanford, CA, United States of America
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
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9
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Shah NP, Brackbill N, Samarakoon R, Rhoades C, Kling A, Sher A, Litke A, Singer Y, Shlens J, Chichilnisky EJ. Individual variability of neural computations in the primate retina. Neuron 2022; 110:698-708.e5. [PMID: 34932942 PMCID: PMC8857061 DOI: 10.1016/j.neuron.2021.11.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [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: 01/05/2021] [Revised: 08/10/2021] [Accepted: 11/20/2021] [Indexed: 12/28/2022]
Abstract
Variation in the neural code contributes to making each individual unique. We probed neural code variation using ∼100 population recordings from major ganglion cell types in the macaque retina, combined with an interpretable computational representation of individual variability. This representation captured variation and covariation in properties such as nonlinearity, temporal dynamics, and spatial receptive field size and preserved invariances such as asymmetries between On and Off cells. The covariation of response properties in different cell types was associated with the proximity of lamination of their synaptic input. Surprisingly, male retinas exhibited higher firing rates and faster temporal integration than female retinas. Exploiting data from previously recorded retinas enabled efficient characterization of a new macaque retina, and of a human retina. Simulations indicated that combining a large dataset of retinal recordings with behavioral feedback could reveal the neural code in a living human and thus improve vision restoration with retinal implants.
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Affiliation(s)
- Nishal P Shah
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA; Hansen Experimental Physics Lab, Stanford University, Stanford, CA 94305, USA; Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA.
| | - Nora Brackbill
- Hansen Experimental Physics Lab, Stanford University, Stanford, CA 94305, USA; Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Ryan Samarakoon
- Hansen Experimental Physics Lab, Stanford University, Stanford, CA 94305, USA; Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA
| | - Colleen Rhoades
- Hansen Experimental Physics Lab, Stanford University, Stanford, CA 94305, USA; Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Alexandra Kling
- Hansen Experimental Physics Lab, Stanford University, Stanford, CA 94305, USA; Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA
| | - Alexander Sher
- University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Alan Litke
- University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Yoram Singer
- WorldQuant, LLC, 1700 E Putnam Ave., Old Greenwich, CT 06870, USA
| | - Jonathon Shlens
- Google Brain, 1600 Amphitheatre Pkwy., Mountain View, CA 94043, USA
| | - E J Chichilnisky
- Hansen Experimental Physics Lab, Stanford University, Stanford, CA 94305, USA; Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA
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10
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Brackbill N, Rhoades C, Kling A, Shah NP, Sher A, Litke AM, Chichilnisky EJ. Reconstruction of natural images from responses of primate retinal ganglion cells. eLife 2020; 9:e58516. [PMID: 33146609 PMCID: PMC7752138 DOI: 10.7554/elife.58516] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Accepted: 11/02/2020] [Indexed: 11/23/2022] Open
Abstract
The visual message conveyed by a retinal ganglion cell (RGC) is often summarized by its spatial receptive field, but in principle also depends on the responses of other RGCs and natural image statistics. This possibility was explored by linear reconstruction of natural images from responses of the four numerically-dominant macaque RGC types. Reconstructions were highly consistent across retinas. The optimal reconstruction filter for each RGC - its visual message - reflected natural image statistics, and resembled the receptive field only when nearby, same-type cells were included. ON and OFF cells conveyed largely independent, complementary representations, and parasol and midget cells conveyed distinct features. Correlated activity and nonlinearities had statistically significant but minor effects on reconstruction. Simulated reconstructions, using linear-nonlinear cascade models of RGC light responses that incorporated measured spatial properties and nonlinearities, produced similar results. Spatiotemporal reconstructions exhibited similar spatial properties, suggesting that the results are relevant for natural vision.
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Affiliation(s)
- Nora Brackbill
- Department of Physics, Stanford UniversityStanfordUnited States
| | - Colleen Rhoades
- Department of Bioengineering, Stanford UniversityStanfordUnited States
| | - Alexandra Kling
- Department of Neurosurgery, Stanford School of MedicineStanfordUnited States
- Department of Ophthalmology, Stanford UniversityStanfordUnited States
- Hansen Experimental Physics Laboratory, Stanford UniversityStanfordUnited States
| | - Nishal P Shah
- Department of Electrical Engineering, Stanford UniversityStanfordUnited States
| | - Alexander Sher
- Santa Cruz Institute for Particle Physics, University of California, Santa CruzSanta CruzUnited States
| | - Alan M Litke
- Santa Cruz Institute for Particle Physics, University of California, Santa CruzSanta CruzUnited States
| | - EJ Chichilnisky
- Department of Neurosurgery, Stanford School of MedicineStanfordUnited States
- Department of Ophthalmology, Stanford UniversityStanfordUnited States
- Hansen Experimental Physics Laboratory, Stanford UniversityStanfordUnited States
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11
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Shah NP, Brackbill N, Rhoades C, Kling A, Goetz G, Litke AM, Sher A, Simoncelli EP, Chichilnisky EJ. Inference of nonlinear receptive field subunits with spike-triggered clustering. eLife 2020; 9:e45743. [PMID: 32149600 PMCID: PMC7062463 DOI: 10.7554/elife.45743] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Accepted: 10/29/2019] [Indexed: 11/25/2022] Open
Abstract
Responses of sensory neurons are often modeled using a weighted combination of rectified linear subunits. Since these subunits often cannot be measured directly, a flexible method is needed to infer their properties from the responses of downstream neurons. We present a method for maximum likelihood estimation of subunits by soft-clustering spike-triggered stimuli, and demonstrate its effectiveness in visual neurons. For parasol retinal ganglion cells in macaque retina, estimated subunits partitioned the receptive field into compact regions, likely representing aggregated bipolar cell inputs. Joint clustering revealed shared subunits between neighboring cells, producing a parsimonious population model. Closed-loop validation, using stimuli lying in the null space of the linear receptive field, revealed stronger nonlinearities in OFF cells than ON cells. Responses to natural images, jittered to emulate fixational eye movements, were accurately predicted by the subunit model. Finally, the generality of the approach was demonstrated in macaque V1 neurons.
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Affiliation(s)
- Nishal P Shah
- Department of Electrical EngineeringStanford UniversityStanfordUnited States
| | - Nora Brackbill
- Department of PhysicsStanford UniversityStanfordUnited States
| | - Colleen Rhoades
- Department of BioengineeringStanford UniversityStanfordUnited States
| | - Alexandra Kling
- Department of NeurosurgeryStanford School of MedicineStanfordUnited States
- Department of OphthalmologyStanford UniversityStanfordUnited States
- Hansen Experimental Physics LaboratoryStanford UniversityStanfordUnited States
| | - Georges Goetz
- Department of NeurosurgeryStanford School of MedicineStanfordUnited States
- Department of OphthalmologyStanford UniversityStanfordUnited States
- Hansen Experimental Physics LaboratoryStanford UniversityStanfordUnited States
| | - Alan M Litke
- Institute for Particle PhysicsUniversity of California, Santa CruzSanta CruzUnited States
| | - Alexander Sher
- Santa Cruz Institute for Particle PhysicsUniversity of California, Santa CruzSanta CruzUnited States
| | - Eero P Simoncelli
- Center for Neural ScienceNew York UniversityNew YorkUnited States
- Howard Hughes Medical InstituteChevy ChaseUnited States
| | - EJ Chichilnisky
- Department of NeurosurgeryStanford School of MedicineStanfordUnited States
- Department of OphthalmologyStanford UniversityStanfordUnited States
- Hansen Experimental Physics LaboratoryStanford UniversityStanfordUnited States
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12
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Rhoades CE, Shah NP, Manookin MB, Brackbill N, Kling A, Goetz G, Sher A, Litke AM, Chichilnisky EJ. Unusual Physiological Properties of Smooth Monostratified Ganglion Cell Types in Primate Retina. Neuron 2019; 103:658-672.e6. [PMID: 31227309 PMCID: PMC6817368 DOI: 10.1016/j.neuron.2019.05.036] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [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: 12/20/2018] [Revised: 04/26/2019] [Accepted: 05/22/2019] [Indexed: 02/06/2023]
Abstract
The functions of the diverse retinal ganglion cell types in primates and the parallel visual pathways they initiate remain poorly understood. Here, unusual physiological and computational properties of the ON and OFF smooth monostratified ganglion cells are explored. Large-scale multi-electrode recordings from 48 macaque retinas revealed that these cells exhibit irregular receptive field structure composed of spatially segregated hotspots, quite different from the classic center-surround model of retinal receptive fields. Surprisingly, visual stimulation of different hotspots in the same cell produced spikes with subtly different spatiotemporal voltage signatures, consistent with a dendritic contribution to hotspot structure. Targeted visual stimulation and computational inference demonstrated strong nonlinear subunit properties associated with each hotspot, supporting a model in which the hotspots apply nonlinearities at a larger spatial scale than bipolar cells. These findings reveal a previously unreported nonlinear mechanism in the output of the primate retina that contributes to signaling spatial information.
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Affiliation(s)
- Colleen E Rhoades
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA.
| | - Nishal P Shah
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Michael B Manookin
- Department of Ophthalmology, University of Washington, Seattle, WA 98195, USA
| | - Nora Brackbill
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Alexandra Kling
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA; Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
| | - Georges Goetz
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA; Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
| | - Alexander Sher
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Alan M Litke
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - E J Chichilnisky
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA; Department of Ophthalmology Stanford University, Stanford, CA 94305, USA; Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
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13
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Abstract
Daylight vision begins when light activates cone photoreceptors in the retina, creating spatial patterns of neural activity. These cone signals are then combined and processed in downstream neural circuits, ultimately producing visual perception. Recent technical advances have made it possible to deliver visual stimuli to the retina that probe this processing by the visual system at its elementary resolution of individual cones. Physiological recordings from nonhuman primate retinas reveal the spatial organization of cone signals in retinal ganglion cells, including how signals from cones of different types are combined to support both spatial and color vision. Psychophysical experiments with human subjects characterize the visual sensations evoked by stimulating a single cone, including the perception of color. Future combined physiological and psychophysical experiments focusing on probing the elementary visual inputs are likely to clarify how neural processing generates our perception of the visual world.
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Affiliation(s)
- A Kling
- Departments of Neurosurgery and Ophthalmology, Stanford University School of Medicine, Stanford, California 94305, USA;
| | - G D Field
- Department of Neurobiology, Duke University School of Medicine, Durham, North Carolina 27710, USA
| | - D H Brainard
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - E J Chichilnisky
- Departments of Neurosurgery and Ophthalmology, Stanford University School of Medicine, Stanford, California 94305, USA;
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14
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Morlat T, Fernandes AC, Felizardo M, Kling A, Girard TA, Marques JG, Carvalho FP. APPLICATION OF DROPLET DETECTORS TO ALPHA RADIATION DETECTION. Radiat Prot Dosimetry 2018; 180:230-234. [PMID: 29149344 DOI: 10.1093/rpd/ncx253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Indexed: 06/07/2023]
Abstract
Superheated droplet detectors (SDDs) are traditionally employed in the detection of neutrons. In this work the focus is on the detection of alpha particles using C2ClF5 as the target liquid. The alpha-droplet interaction is examined via computational studies, and a geometric model developed to describe the expected detector response. Experiments with alpha-emitting uranium- and samarium-doped SDDs at temperatures of 5-12°C confirm that the event rate is related to the size of the droplets, and are in model agreement for temperatures below 8°C; above this temperature, the acoustic sensitivity is reduced by signal attenuation as a result of the increasing bubble population, for which the addition of an attenuation coefficient restores the agreement with experiment. The results suggest the viability of a SDD-based alpha spectrometer using mono-sized droplets.
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Affiliation(s)
- T Morlat
- C2TN, Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, Bobadela LRS, Portugal
| | - A C Fernandes
- C2TN, Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, Bobadela LRS, Portugal
| | - M Felizardo
- C2TN, Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, Bobadela LRS, Portugal
| | - A Kling
- C2TN, Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, Bobadela LRS, Portugal
| | - T A Girard
- C 2 TN, Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, Bobadela LRS, Portugal
- Departamento de Fisica, Universidade de Lisboa, Lisboa, Portugal
| | - J G Marques
- C2TN, Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, Bobadela LRS, Portugal
| | - F P Carvalho
- C2TN, Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, Bobadela LRS, Portugal
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15
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Bruch R, Chatelle C, Kling A, Rebmann B, Wirth S, Schumann S, Weber W, Dincer C, Urban G. Clinical on-site monitoring of ß-lactam antibiotics for a personalized antibiotherapy. Sci Rep 2017; 7:3127. [PMID: 28600499 PMCID: PMC5466632 DOI: 10.1038/s41598-017-03338-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [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: 02/01/2017] [Accepted: 04/26/2017] [Indexed: 01/07/2023] Open
Abstract
An appropriate antibiotherapy is crucial for the safety and recovery of patients. Depending on the clinical conditions of patients, the required dose to effectively eradicate an infection may vary. An inadequate dosing not only reduces the efficacy of the antibiotic, but also promotes the emergence of antimicrobial resistances. Therefore, a personalized therapy is of great interest for improved patients' outcome and will reduce in long-term the prevalence of multidrug-resistances. In this context, on-site monitoring of the antibiotic blood concentration is fundamental to facilitate an individual adjustment of the antibiotherapy. Herein, we present a bioinspired approach for the bedside monitoring of free accessible ß-lactam antibiotics, including penicillins (piperacillin) and cephalosporins (cefuroxime and cefazolin) in untreated plasma samples. The introduced system combines a disposable microfluidic chip with a naturally occurring penicillin-binding protein, resulting in a high-performance platform, capable of gauging very low antibiotic concentrations (less than 6 ng ml-1) from only 1 µl of serum. The system's applicability to a personalized antibiotherapy was successfully demonstrated by monitoring the pharmacokinetics of patients, treated with ß-lactam antibiotics, undergoing surgery.
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Affiliation(s)
- R Bruch
- Department of Microsystems Engineering, University of Freiburg, 79110, Freiburg, Germany
| | - C Chatelle
- Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany
| | - A Kling
- Department of Biosystems Science and Engineering, ETH Zurich, 4058, Basel, Switzerland
| | - B Rebmann
- Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany
| | - S Wirth
- Department of Anaesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, 79106, Freiburg, Germany
| | - S Schumann
- Department of Anaesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, 79106, Freiburg, Germany
| | - W Weber
- Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany
| | - C Dincer
- Department of Microsystems Engineering, University of Freiburg, 79110, Freiburg, Germany. .,Freiburg Materials Research Center, University of Freiburg, 79104, Freiburg, Germany.
| | - G Urban
- Department of Microsystems Engineering, University of Freiburg, 79110, Freiburg, Germany.,Freiburg Materials Research Center, University of Freiburg, 79104, Freiburg, Germany
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16
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Blaauw M, Ridikas D, Baytelesov S, Salas PSB, Chakrova Y, Eun-Ha C, Dahalan R, Fortunato AH, Jacimovic R, Kling A, Muñoz L, Mohamed NMA, Párkányi D, Singh T, Van Dong Duong. Estimation of 99Mo production rates from natural molybdenum in research reactors. J Radioanal Nucl Chem 2016; 311:409-418. [PMID: 28111485 PMCID: PMC5219034 DOI: 10.1007/s10967-016-5036-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Indexed: 11/29/2022]
Abstract
Molybdenum-99 is one of the most important radionuclides for medical diagnostics. In 2015, the International Atomic Energy Agency organized a round-robin exercise where the participants measured and calculated specific saturation activities achievable for the 98Mo(n,γ)99Mo reaction. This reaction is of interest as a means to locally, and on a small scale, produce 99Mo from natural molybdenum. The current paper summarises a set of experimental results and reviews the methodology for calculating the corresponding saturation activities. Activation by epithermal neutrons and also epithermal neutron self-shielding are found to be of high importance in this case.
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Affiliation(s)
- M Blaauw
- Reactor Institute Delft, Delft University of Technology, Mekelweg 15, 2629 JB Delft, The Netherlands
| | - D Ridikas
- Division of Physical and Chemical Sciences, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - S Baytelesov
- Institute of Nuclear Physics, Academy of Sciences of Uzbekistan, Ulug Gulomov Str., Tashkent, Uzbekistan 100214
| | - P S Bedregal Salas
- Instituto Peruano de Energia Nuclear, Avenida Canadá 1470, 41, Lima, Peru
| | - Y Chakrova
- Institute of Nuclear Physics of Ministry of Energy of the Republic of Kazakhstan, Ibragimova 1, Almaty, Kazakhstan 050032
| | - Cho Eun-Ha
- RI Research Division, Korea Atomic Energy Research Institute, 989-111, Daedeok-daero, Yuseong-gu, Daejeon 305-353 Korea
| | - R Dahalan
- Medical Technology Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor Malaysia
| | - A H Fortunato
- Instituto Nacionale de Investigciones Nucleares, Carretera Mexico-Toluca S/N La Marquesa, Ocoyoacac, Mexico
| | - R Jacimovic
- Jozef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia
| | - A Kling
- Centro de Ciências e Tecnologias Nucleares and Laboratório de Engenharia Nuclear, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10 ao km 139,7,, 2695-066 Bobadela LRS, Portugal
| | - L Muñoz
- Comisión Chilena de Energía Nuclear (CCHEN), Avenida Nueva Bilbao No. 12501, Las Condes, Santiago, Chile
| | - N M A Mohamed
- Egypt Second Research Reactor (ETRR-2), Atomic Energy Authority (AEA), Abou Zabal, Cairo, 13759 Egypt
| | - D Párkányi
- Centre for Energy Research, Hungarian Academy of Sciences, Konkoly Thege Miklós út 29-33, Budapest, 1121 Hungary
| | - T Singh
- Department of Atomic Energy (DAE), Bhabha Atomic Research Centre (BARC), Trombay, Mumbai, Maharashtra 400 085 India
| | - Van Dong Duong
- Vietnam Atomic Energy Institute, 01 Nguyen Tu Luc, Dalat, Vietnam
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17
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Dincer C, Kling A, Chatelle C, Armbrecht L, Kieninger J, Weber W, Urban GA. Designed miniaturization of microfluidic biosensor platforms using the stop-flow technique. Analyst 2016; 141:6073-6079. [DOI: 10.1039/c6an01330a] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Here, we present a novel approach to increase the degree of miniaturization as well as the sensitivity of biosensor platforms by the optimization of microfluidic stop-flow techniques independent of the applied detection technique (e.g. electrochemical or optical).
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Affiliation(s)
- C. Dincer
- Laboratory for Sensors
- Department of Microsystems Engineering - IMTEK
- University of Freiburg
- Germany
- Freiburg Materials Research Center - FMF
| | - A. Kling
- Laboratory for Sensors
- Department of Microsystems Engineering - IMTEK
- University of Freiburg
- Germany
| | - C. Chatelle
- Centre for Biological Signalling Studies - BIOSS
- Germany
- Faculty of Biology
- University of Freiburg
- Germany
| | - L. Armbrecht
- Laboratory for Sensors
- Department of Microsystems Engineering - IMTEK
- University of Freiburg
- Germany
| | - J. Kieninger
- Laboratory for Sensors
- Department of Microsystems Engineering - IMTEK
- University of Freiburg
- Germany
| | - W. Weber
- Centre for Biological Signalling Studies - BIOSS
- Germany
- Faculty of Biology
- University of Freiburg
- Germany
| | - G. A. Urban
- Laboratory for Sensors
- Department of Microsystems Engineering - IMTEK
- University of Freiburg
- Germany
- Freiburg Materials Research Center - FMF
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18
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Armbrecht L, Dincer C, Kling A, Horak J, Kieninger J, Urban G. Self-assembled magnetic bead chains for sensitivity enhancement of microfluidic electrochemical biosensor platforms. Lab Chip 2015; 15:4314-4321. [PMID: 26394820 DOI: 10.1039/c5lc00796h] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this paper, we present a novel approach to enhance the sensitivity of microfluidic biosensor platforms with self-assembled magnetic bead chains. An adjustable, more than 5-fold sensitivity enhancement is achieved by introducing a magnetic field gradient along a microfluidic channel by means of a soft-magnetic lattice with a 350 μm spacing. The alternating magnetic field induces the self-assembly of the magnetic beads in chains or clusters and thus improves the perfusion and active contact between the analyte and the beads. The soft-magnetic lattices can be applied independent of the channel geometry or chip material to any microfluidic biosensing platform. At the same time, the bead-based approach achieves chip reusability and shortened measurement times. The bead chain properties and the maximum flow velocity for bead retention were validated by optical microscopy in a glass capillary. The magnetic actuation system was successfully validated with a biotin-streptavidin model assay on a low-cost electrochemical microfluidic chip, fabricated by dry-film photoresist technology (DFR). Labelling with glucose oxidase (GOx) permits rapid electrochemical detection of enzymatically produced H2O2.
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Affiliation(s)
- L Armbrecht
- Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110 Freiburg, Germany.
| | - C Dincer
- Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110 Freiburg, Germany. and Freiburg Materials Research Center - FMF, University of Freiburg, 79110 Freiburg, Germany
| | - A Kling
- Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110 Freiburg, Germany.
| | - J Horak
- Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110 Freiburg, Germany. and Division of Chemical Protein Engineering, KTH Stockholm, Stockholm, Sweden
| | - J Kieninger
- Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110 Freiburg, Germany.
| | - G Urban
- Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110 Freiburg, Germany. and Freiburg Materials Research Center - FMF, University of Freiburg, 79110 Freiburg, Germany
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19
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Gherasim A, Lebbad M, Insulander M, Decraene V, Kling A, Hjertqvist M, Wallensten A. Two geographically separated food-borne outbreaks in Sweden linked by an unusual Cryptosporidium parvum subtype, October 2010. Euro Surveill 2012; 17. [DOI: 10.2807/ese.17.46.20318-en] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Binary file ES_Abstracts_Final_ECDC.txt matches
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Affiliation(s)
- A Gherasim
- Department of Analysis and Prevention, Swedish Institute for Communicable Disease Control (SMI), Solna, Sweden
- European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden
| | - M Lebbad
- Department of Diagnostics and Vaccinology, Swedish Institute for Communicable Disease Control, Solna, Sweden
| | - M Insulander
- Department of Communicable Disease Control and Prevention, Stockholm County, Sweden
| | - V Decraene
- Department of Analysis and Prevention, Swedish Institute for Communicable Disease Control (SMI), Solna, Sweden
- European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden
| | - A Kling
- Department of Analysis and Prevention, Swedish Institute for Communicable Disease Control (SMI), Solna, Sweden
| | - M Hjertqvist
- Department of Analysis and Prevention, Swedish Institute for Communicable Disease Control (SMI), Solna, Sweden
| | - A Wallensten
- Uppsala University, Uppsala, Sweden
- Department of Analysis and Prevention, Swedish Institute for Communicable Disease Control (SMI), Solna, Sweden
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20
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Felizardo M, Girard TA, Morlat T, Fernandes AC, Ramos AR, Marques JG, Kling A, Puibasset J, Auguste M, Boyer D, Cavaillou A, Poupeney J, Sudre C, Miley HS, Payne RF, Carvalho FP, Prudêncio MI, Gouveia A, Marques R. Final analysis and results of the Phase II SIMPLE dark matter search. Phys Rev Lett 2012; 108:201302. [PMID: 23003137 DOI: 10.1103/physrevlett.108.201302] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 03/15/2012] [Indexed: 06/01/2023]
Abstract
We report the final results of the Phase II SIMPLE measurements, comprising two run stages of 15 superheated droplet detectors each, with the second stage including an improved neutron shielding. The analyses include a refined signal analysis, and revised nucleation efficiency based on a reanalysis of previously reported monochromatic neutron irradiations. The combined results yield a contour minimum of σp=5.7×10(-3) pb at 35 GeV/c2 in the spin-dependent sector of weakly interacting massive particle (WIMP) proton interactions, the most restrictive to date for MW}≤60 GeV/c2 from a direct search experiment and overlapping, for the first time, with results previously obtained only indirectly. In the spin-independent sector, a minimum of 4.7×10(-6) pb at 35 GeV/c2 is achieved, with the exclusion contour challenging a significant part of the light mass WIMP region of current interest.
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Affiliation(s)
- M Felizardo
- Department of Physics, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal and Centro de Física Nuclear, Universidade de Lisboa, 1649-003 Lisbon, Portugal
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21
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Meister H, Penzel F, Giannone L, Kannamüller M, Kling A, Koll J, Trautmann T. Development of an automated method for in situ measurement of the geometrical properties of the ITER bolometer diagnostic. Fusion Engineering and Design 2011. [DOI: 10.1016/j.fusengdes.2010.12.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Meister H, Eich T, Endstrasser N, Giannone L, Kannamüller M, Kling A, Koll J, Trautmann T, Detemple P, Schmitt S. Optimization of a bolometer detector for ITER based on Pt absorber on SiN membrane. Rev Sci Instrum 2010; 81:10E132. [PMID: 21061487 DOI: 10.1063/1.3499637] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Any plasma diagnostic in ITER must be able to operate at temperatures in excess of 200 °C and neutron loads corresponding to 0.1 dpa over its lifetime. To achieve this aim for the bolometer diagnostic, a miniaturized metal resistor bolometer detector based on Pt absorbers galvanically deposited on SiN membranes is being developed. The first two generations of detectors featured up to 4.5 μm thick absorbers. Results from laboratory tests are presented characterizing the dependence of their calibration constants under thermal loads up to 450 °C. Several detectors have been tested in ASDEX Upgrade providing reliable data but also pointing out the need for further optimization. A laser trimming procedure has been implemented to reduce the mismatch in meander resistances below 1% for one detector and the thermal drifts from this mismatch.
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Affiliation(s)
- H Meister
- Max-Planck-Institut für Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching, Germany.
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Fernandes A, Santos J, Marques J, Kling A, Ramos A, Barradas N. Validation of the Monte Carlo model supporting core conversion of the Portuguese Research Reactor (RPI) for neutron fluence rate determinations. ANN NUCL ENERGY 2010. [DOI: 10.1016/j.anucene.2010.05.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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24
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Kling A, Seddighzadeh M, Arlestig L, Alfredsson L, Rantapaa-Dahlqvist S, Padyukov L. Genetic variations in the serotonin 5-HT2A receptor gene (HTR2A) are associated with rheumatoid arthritis. Ann Rheum Dis 2008; 67:1111-5. [DOI: 10.1136/ard.2007.074948] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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25
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Goldacker W, Frank A, Heller R, Ringsdorf B, Schlachter SI, Kling A, Schmidt C, Balachandran U(B, Amm K, Evans D, Gregory E, Lee P, Osofsky M, Pamidi S, Park C, Wu J, Sumption M. CRITICAL CURRENTS IN ROEBEL ASSEMBLED COATED CONDUCTORS (RACC). ACTA ACUST UNITED AC 2008. [DOI: 10.1063/1.2900383] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Abstract
BACKGROUND Animal studies have indicated that 5-HT2A receptors could play a role in arthritic diseases. OBJECTIVE To analyse the binding properties of 5-HT2A receptors in patients with rheumatoid arthritis. METHODS Using a radioactive binding assay, 43 patients with rheumatoid arthritis were compared with 49 sex and age matched controls for density and affinity (measured as Bmax and Kd) of 5-HT2A serotonin receptors. Genotyping, using polymerase chain reaction, was undertaken to exclude the possibility that differences in the genetic polymorphism T102C for the 5-HT2A receptor determine differences in receptor density. RESULTS Mean of Bmax of 5-HT2A receptors in rheumatoid patients was significantly lower than in controls, at 45.3 v 57.4 fmol/mg protein (p = 0.004), but there was no significant difference in Kd. The T102C receptor polymorphism genotypes showed a skewed distribution between the two groups. Even when adjusted for this, there was a significant difference in Bmax between the groups. CONCLUSIONS The density of 5-HT2A serotonin receptors in patients with rheumatoid arthritis is markedly reduced. This could either reflect a difference involved in the susceptibility to the disease or be a secondary effect of the disease.
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Affiliation(s)
- A Kling
- Division of Clinical Pharmacology, Umeå University Hospital, S-901 85 Umeå, Sweden.
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27
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Fernandes AC, Gonçalves IC, Santos J, Cardoso J, Santos L, Ferro Carvalho A, Marques JG, Kling A, Ramalho AJG, Osvay M. Dosimetry at the Portuguese research reactor using thermoluminescence measurements and Monte Carlo calculations. Radiat Prot Dosimetry 2006; 120:349-53. [PMID: 16702246 DOI: 10.1093/rpd/nci560] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
This work presents an extensive study on Monte Carlo radiation transport simulation and thermoluminescent (TL) dosimetry for characterising mixed radiation fields (neutrons and photons) occurring in nuclear reactors. The feasibility of these methods is investigated for radiation fields at various locations of the Portuguese Research Reactor (RPI). The performance of the approaches developed in this work is compared with dosimetric techniques already existing at RPI. The Monte Carlo MCNP-4C code was used for a detailed modelling of the reactor core, the fast neutron beam and the thermal column of RPI. Simulations using these models allow to reproduce the energy and spatial distributions of the neutron field very well (agreement better than 80%). In the case of the photon field, the agreement improves with decreasing intensity of the component related to fission and activation products. (7)LiF:Mg,Ti, (7)LiF:Mg,Cu,P and Al(2)O(3):Mg,Y TL detectors (TLDs) with low neutron sensitivity are able to determine photon dose and dose profiles with high spatial resolution. On the other hand, (nat)LiF:Mg,Ti TLDs with increased neutron sensitivity show a remarkable loss of sensitivity and a high supralinearity in high-intensity fields hampering their application at nuclear reactors.
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Affiliation(s)
- A C Fernandes
- Instituto Tecnológico e Nuclear, Estrada Nacional 10, P-2686-953 Sacavém, Portugal.
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29
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Kling A, Dahlqvist R, Johansson S, Bäckström M, Mjörndal T. Neurologic oral manifestations caused by a new formulation of mirtazapine. Neurology 2005; 65:333-4. [PMID: 16043818 DOI: 10.1212/01.wnl.0000168843.27680.7a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- A Kling
- Division of Clinical Pharmacology, Department of Pharmacology and Clinical Neurosciences, Umeå University, Umeå, Sweden.
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30
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Kling A, Mjörndal T, Rantapää-Dahlqvist S. Sepsis as a Possible Adverse Drug Reaction in Patients With Rheumatoid Arthritis Treated With TNFα Antagonists. J Clin Rheumatol 2004; 10:119-22. [PMID: 17043483 DOI: 10.1097/01.rhu.0000128734.07926.8e] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Clinical improvement during the treatment of rheumatoid arthritis (RA) with the TNFalpha antagonists has been well documented. Our knowledge of uncommon adverse drug reactions (ADRs) with these new drugs is more restricted. Concerns have been raised that these types of drugs could cause an increased frequency of infections, and already existing infections are named as contraindications in the product labels. METHODS In Sweden, it is compulsory for healthcare professionals with permission to prescribe drugs to report suspected ADRs to the regulatory authority, the Medical Product Agency (MPA). At the 6 regional centers that are established in Sweden, a preliminary causality assessment is made and the data is transferred online to a database. RESULTS Between January 1, 1999, and June 30, 2003, 29 cases of sepsis were reported as suspected adverse effects caused by drugs. Seventeen of these cases concerned TNFalpha antagonists. The MPA has received 3 reports of septicemia in patients from Northern Sweden treated with the TNFalpha antagonist etanercept. In submitting these reports, factors that can contribute to susceptibility and to more fatal courses of serious infections are taken into consideration. Demographic and pharmaceutical factors as well as risks from predisposing conditions are discussed in connection with the cases in this report. CONCLUSION There is a need for more information to physicians to be aware of sepsis as a possible and serious ADR during treatment with TNF antagonists, and that patients with predisposing diseases or those who do not regularly visit their rheumatologist could be at higher risk.
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Affiliation(s)
- A Kling
- Division of Clinical Pharmacology, Norrland University Hospital, Umeå, Sweden.
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31
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Fernandes AC, Santos JP, Kling A, Marques JG, Gonçalves IC, Carvalho AF, Santos L, Cardoso J, Osvay M. Thermoluminescence dosimetry of a thermal neutron field and comparison with Monte Carlo calculations. Radiat Prot Dosimetry 2004; 111:35-39. [PMID: 15367765 DOI: 10.1093/rpd/nch356] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The characteristics of thermoluminescence dosemeters (TLDs) regarding the determination of photon and neutron absorbed doses were investigated in a thermal neutron beam. Harshaw TLD-100 (LiF:Mg,Ti) and TLD-700 (7LiF:Mg,Ti) were compared with similar materials from Solid Dosimetric Detector and Method Laboratory (People's Republic of China). Harshaw TLD-700H (7LiF:Mg,Cu,P) and aluminium oxide (Al2O3:Mg,Y) from Hungary were also considered for photon dose measurement. The neutron sensitivity of the investigated materials was measured and found to be consistent with values reported by other authors. A comparison was made between the TL dose measurements and results obtained via conventional methods. An agreement within 20% was obtained, which demonstrates the ability of TLD for measuring neutron and photon doses in a mixed field, using careful calibration procedures and determining the neutron sensitivity for the usage conditions.
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Affiliation(s)
- A C Fernandes
- Instituto Tecnológico e Nuclear, Estrada Nacional 10, P-2686-953 Sacavém, Portugal.
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Abstract
A fundamental task within the framework of a project searching for new radiopharmaceuticals for systemic therapy was the evaluation of the capabilities of the Portuguese Research Reactor (RPI) for the production of several important radionuclides. The feasibility of producing 64Cu, 77As, 153Sm, 165Dy, 166Ho, 170Tm, 177Lu, 186Re, 199Au and 111Ag in useful quantities was evaluated for the present RPI operation schedule (12 h cycles) and for continuous operation. The main evaluation criteria are expressed in terms of specific activity for continuous irradiation and/or 12 h cycle and the use of natural or enriched targets if necessary. Selected samples were irradiated and a comparison between measured activities and values calculated according to the irradiation schedule and using the same software was performed.
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Affiliation(s)
- M Neves
- Instituto Tecnológico e Nuclear, Sacavém, Portugal.
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33
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Kessler H, Matter H, Gemmecker G, Kling A, Kottenhahn M. Solution structure of a synthetic N-glycosylated cyclic hexapeptide determined by NMR spectroscopy and MD calculations. J Am Chem Soc 2002. [DOI: 10.1021/ja00020a016] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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34
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Sachinvala N, Kling A, Suffin S, Lake R, Cohen M. Increased regional cerebral perfusion by 99mTc hexamethyl propylene amine oxime single photon emission computed tomography in post-traumatic stress disorder. Mil Med 2000; 165:473-9. [PMID: 10870367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
OBJECTIVE Because of the treatment resistance and chronic affective lability of many post-traumatic stress disorder (PTSD) patients and the hypothesized association of these behaviors with temporal and limbic structures, a study was conducted to determine whether these patients would exhibit alterations in regional cerebral perfusion in the temporal and limbic regions compared with age-matched normal volunteers at rest. METHOD We studied 17 patients using 99mTc hexamethyl propylene amine oxime single photon emission computed tomography. Seven of the patients were on a selective serotonin reuptake inhibitor, five were on a tricyclic antidepressant, and five were on no medication at the time of the study. Patients were compared with eight age-matched normal controls. RESULTS All PTSD patients showed a relative increase in regional cerebral perfusion in the anterior and posterior cingulate regions bilaterally, the right temporal and parietal regions, the right caudate/putamen region, and the left orbital and hippocampal regions compared with the control group. When the group of PTSD patients who were free of medication were compared with the control group, increased regional cerebral perfusion was found in the right and left caudate/putamen regions and the right orbital and anterior cingulate cortex bilaterally. CONCLUSIONS PTSD is associated with increased regional blood flow in limbic areas and the right temporal and parietal cortex compared with age-matched normal volunteers.
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Affiliation(s)
- N Sachinvala
- Sepulveda Veterans Affairs Medical Center, CA, USA
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35
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Amberg W, Hergenröder S, Hillen H, Jansen R, Kettschau G, Kling A, Klinge D, Raschack M, Riechers H, Unger L. Discovery and synthesis of (S)-3-[2-(3,4-dimethoxyphenyl)ethoxy]-2- (4,6-dimethylpyrimidin-2-yloxy)-3,3-diphenylpropionic acid (LU 302872), a novel orally active mixed ET(A)/ET(B) receptor antagonist. J Med Chem 1999; 42:3026-32. [PMID: 10447946 DOI: 10.1021/jm9910425] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Structural variation of the endothelin A-selective antagonist (S)-3-methoxy-2-(4,6-dimethoxypyrimidin-2-yloxy)-3, 3-diphenylpropionic acid (LU 135252) led to analogues which retain ET(A) affinity but exhibit substantial ET(B) affinity as well. The most active derivative obtained is (S)-3-[2-(3, 4-dimethoxyphenyl)ethoxy]-2-(4,6-dimethylpyrimidin-2-yloxy)- 3, 3-diphenylpropionic acid (LU 302872), which can be prepared in enantiomerically pure form in eight steps via an acid-catalyzed transetherification. It has a K(i) = 2.15 nM for binding to the ET(A) receptor and a K(i) = 4.75 nM for binding to the ET(B) receptor, is orally available, and antagonizes the big ET-induced blood pressure increase in rats and the big ET-induced bronchospasm in guinea pigs each time at a dose of 10 mg/kg.
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Affiliation(s)
- W Amberg
- Hauptlaboratorium, BASF AG, 67056 Ludwigshafen, Germany, and Knoll AG, 67008 Ludwigshafen, Germany.
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36
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Riechers H, Albrecht HP, Amberg W, Baumann E, Bernard H, Böhm HJ, Klinge D, Kling A, Müller S, Raschack M, Unger L, Walker N, Wernet W. Discovery and optimization of a novel class of orally active nonpeptidic endothelin-A receptor antagonists. J Med Chem 1996; 39:2123-8. [PMID: 8667356 DOI: 10.1021/jm960274q] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A novel class of endothelin-A receptor ligands was discovered by high-throughput screening. Lead structure optimization led to highly potent antagonists which can be synthesized in a short sequence. The compounds are endothelin-A-selective, are orally available, and show a long duration of action.
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Affiliation(s)
- H Riechers
- Hauptlaboratorium, BASF AG, Ludwigshafen, Germany
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37
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Gross H, Kling A, Henry G, Herndon C, Lavretsky H. Local cerebral glucose metabolism in patients with long-term behavioral and cognitive deficits following mild traumatic brain injury. J Neuropsychiatry Clin Neurosci 1996; 8:324-34. [PMID: 8854305 DOI: 10.1176/jnp.8.3.324] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A retrospective study of 20 patients with mild traumatic brain injury (MTBI) examined brain regions of interest by comparing [18F]-2-deoxyglucose PET, neuropsychological test results, and continuing behavioral dysfunction. Abnormal local cerebral metabolic rates (rLCMs) were most prominent in midtemporal, anterior cingulate, precuneus, anterior temporal, frontal white, and corpus callosum brain regions. Abnormal rLCMs were significantly correlated statistically with 1) overall clinical complaints, most specifically with inconsistent attention/concentration and 2) overall neuropsychological test results. The authors conclude that 1) even mild TBI may result in continuing brain behavioral deficits; 2) PET can help elucidate dysfunctional brain circuitry in neurobehavioral disorders; and 3) specific brain areas may correlate with deficits in daily neurobehavioral functioning and neuropsychological test findings.
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Affiliation(s)
- H Gross
- Psychiatry Service, Sepulveda Veterans Administration Medical Center, California, USA
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38
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Hsu B, Kling A, Kessler C, Knapke K, Diefenbach P, Elias JE. Gender differences in sexual fantasy and behavior in a college population: a ten-year replication. J Sex Marital Ther 1994; 20:103-118. [PMID: 8035467 DOI: 10.1080/00926239408403421] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This report is a replication of a study conducted 10 years ago by Person et al., investigating gender differences in sexual behaviors and fantasies in a college population. We found that men continue to fantasize more than women, but the gender differences have narrowed. Recent sexual experiences of our population show a trend toward an increase in gender differences, and there is a greater correlation between sexual fantasy and experiences in women than in men. As in Person's study, we did not find that men had more aggressive/sadistic fantasies than women.
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Affiliation(s)
- B Hsu
- Sepulveda Veterans Affairs Medical Center, Department of Psychiatry, Bakersfield, CA
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39
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Abstract
Working memory is disrupted in Alzheimer's disease and stroke; therefore, any therapeutic drug should restore deficits in working memory. The win-shift foraging paradigm has been demonstrated to be a model of working memory in rats. In the present study, this paradigm was adapted to mice because of the greater ease and economy of testing potential drugs in mice and the wider availability of strains of aged mice with naturally occurring working memory deficits. This study has demonstrated strain differences in the working memory trace and that age induces a deficit that can be detected at 11 months of age in mice. Tacrine and physostigmine enhance the memory trace in normal mice and physostigmine can reverse age-induced working memory deficits in subjects with mild and moderate deficits but not in subjects with severe deficits.
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40
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Kling A, Lloyd R, Tachiki K, Prince H, Klimenko V, Korneva E. Effects of Social Separation on Immune Function and Brain Neurotransmitters in Cebus Monkey (C. Apella). Ann N Y Acad Sci 1992; 650:257-61. [PMID: 1351376 DOI: 10.1111/j.1749-6632.1992.tb49133.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A Kling
- Psychiatry Service, UCLA/Sepulveda Veterans Affairs Medical Center 91343
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41
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Abstract
Eighteen unmedicated chronic schizophrenic patients and 13 normal controls were tested in a paradigm designed to examine functional changes in electroencephalographic (EEG) activity following presentation of emotionally salient auditory stimuli and control tones. Five standard bands of EEG spectral power were examined at bilateral frontal and temporal surface recording sites. The schizophrenic subjects were assigned to diagnostic subgroups on the basis of DSM-III-R criteria following independent clinical examination by two staff psychiatrists. Those subjects who met DSM-III-R criteria for paranoid schizophrenia were assigned to one subgroup (PS subgroup), while those who met DSM-III-R criteria for either residual or undifferentiated schizophrenia were assigned to a second subgroup (R/US subgroup). Analysis of Variance of EEG activity recorded at bilateral frontal (F1 and F2) and temporal (T3 and T4) scalp leads revealed significant diagnosis-related differences in alpha and beta-2 activity at temporal recording sites, and in beta-1 and beta-2 activity at frontal recording sites. Post-hoc tests revealed that significant differences in all four measures occurred in the R/US subgroup, which showed a decrease in temporal alpha and an increase in temporal beta-2 power as compared to controls. These variations in EEG activity appeared to demonstrate a degree of subgroup specificity, as the R/US subgroup also differed significantly from the PS subgroup on most of these measures. Significant subgroup-specific lateralization effects were also observed for temporal lobe delta activity and for frontal lobe beta-1 activity. These findings are interpreted in terms of subgroup-specific alterations in the processing of sensory information in schizophrenia, particularly when such information is emotionally salient. They suggest that subgroup differences in emotional and clinical state may be reflected in differential changes in EEG spectra within the schizophrenic population.
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Affiliation(s)
- C Kessler
- Department of Psychiatry, UCLA School of Medicine 90024
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42
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Caldecott-Hazard S, Guze BH, Kling MA, Kling A, Baxter LR. Clinical and biochemical aspects of depressive disorders: I. Introduction, classification, and research techniques. Synapse 1991; 8:185-211. [PMID: 1948669 DOI: 10.1002/syn.890080306] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The present review focuses on recent data from clinical and animal research concerning the biochemical bases of depressive disorders, diagnosis, and treatment. In addition to integrating these data, problems and future directions in this research are discussed. The review is presented in three parts. This study, Part I, describes diagnostic classification schemes for depressive disorders, some epidemiological and biological correlates of the classifications, and research techniques for investigating depressive disorders. Research techniques include animal models, human biochemical techniques, and Positron Emission Tomography. In a future issue, Part II will discuss various transmitter/receptor theories of depressive disorders, e.g., noradrenergic, serotonergic, cholinergic, and dopaminergic, GABAergic, and peptidergic theories. Also in a future issue, Part III will discuss treatments for depression and some of the controversies in the field.
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Affiliation(s)
- S Caldecott-Hazard
- Laboratory of Biomedical and Environmental Science, University of California, Los Angeles 90024
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43
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Abstract
The presence of neurons in macaque temporal cortex and amygdala which fire selectively in response to social stimuli has been demonstrated by several investigators. The extent to which such neuronal populations may respond to a broad range of social features, including expressive movements and interactions, has not been fully explored due to the difficulty of presenting such complex stimuli in a controlled fashion. We describe a method for presenting moving segments of macaque behavior, visual and auditory, to animal subjects during single unit recording. The method permits a broad range of stimuli to be used both as probes and as controls. In addition, a novel technique for monitoring eye position in alert macaque subjects is described. We present results from the medial amygdala and adjacent cortex, demonstrating that neurons in these regions respond selectively to features of the social environment.
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Affiliation(s)
- L Brothers
- Office of Research-151, UCLA-Sepulveda VA Medical Center 91343
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Buckman TD, Kling A, Sutphin MS, Steinberg A, Eiduson S. Platelet glutathione peroxidase and monoamine oxidase activity in schizophrenics with CT scan abnormalities: relation to psychosocial variables. Psychiatry Res 1990; 31:1-14. [PMID: 1969170 DOI: 10.1016/0165-1781(90)90103-c] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We have previously reported that the activity in platelets of the important antioxidant enzyme glutathione peroxidase (GPx) is inversely correlated with computed tomographic (CT) measures of brain atrophy in a population of patients with chronic schizophrenia, suggesting that low GPx may be a vulnerability factor in those schizophrenic patients with structural brain abnormalities. The significance of this finding has now been explored in a larger clinical population by examining the relation of GPx and CT parameters to psychosocial variables and to the activity of platelet monoamine oxidase (MAO), which has also been reported to be altered in certain schizophrenic populations. In the present study, low platelet GPx and high brain atrophy were found to be associated with DSM-III diagnoses of nonparanoid schizophrenia, a high degree of chronicity, and a predominance of negative symptoms. Contrary to some literature reports, atrophy also correlated with age and length of illness among the schizophrenic patients, although the contribution of these factors was less than that of low GPx, which was itself not age dependent. The ventricle-brain ratio (VBR) and atrophy were highly correlated in a control group of affective disorder patients, but not in the schizophrenic group, where large VBRs were found predominantly in the DSM-III undifferentiated subgroup. The low-GPx/high-atrophy schizophrenic patients had normal platelet MAO levels, and MAO was significantly lower only in the paranoid subgroup, consistent with reported observations. There was no evidence for a neuroleptic-induced effect on either enzyme.
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Affiliation(s)
- T D Buckman
- Department of Neurology, Hahnemann University, Philadelphia, PA 19102-1192
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45
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46
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Abstract
The initial report of the effectiveness of tacrine or tetrahydroaminoacridine (THA) in the treatment of some patients with Alzheimer's disease has been confirmed by further study of additional subjects and by preliminary reports from other investigators. The major side effect, elevation of liver enzymes, is shown to be reversible, dose-dependent and without significant hepatic pathology. Therapeutic serum concentrations of THA vary between 7 and 20 ng/ml. In addition to its presumed action as an acetylcholinesterase inhibitor, data are presented demonstrating marked effects on other brain neurotransmitters in animal models.
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Affiliation(s)
- W K Summers
- Psychiatry Service, Sepulveda VA Medical Center, Los Angeles, Calif
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47
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Abstract
Two groups of heterozygotes, one for metachromatic leukodystrophy (MLD) and the other for Tay-Sachs disease, were given a battery of neuropsychological tests, a standard neurological examination, and an EEG. Neurological and EEG findings were unremarkable for both groups. The MLD heterozygotes showed deficits in the neuropsychological tests involving spatial or constructional components, but not in tests involving language skills. The Tay-Sachs heterozygotes showed no consistent deficit on any component of the neuropsychological tests.
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Affiliation(s)
- H Kohn
- Department of Psychiatry, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway 08854
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48
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Abstract
We studied the effect of chronic, oral administration of 1,2,3,4 tetrahydro-9-aminoacridine (THA), an anticholinesterase, on the acquisition of a color discrimination task in five monkeys (Macaca radiata), aged 13-19 years. A two-phase experiment was performed: initially, one animal was used and served as his own control in a multiple dose, crossover, placebo controlled trial, designed to establish a dose-response curve and an optimal dose range based on THA serum concentrations. Thereafter, four monkeys were given the optimal dose of THA (5.0 mg/day) determined previously while learning up to four color pair discriminations. They also learned up to four other color pair discriminations while on placebo. Two monkeys received THA first, then placebo; the others received placebo first, then THA. No order effects were noted. When combined scores for THA tests were compared to their placebo scores, the difference was significant at p less than 0.01 with all four THA treated monkeys requiring fewer trials to reach learning criterion. These results indicate that THA has a significantly positive effect on the acquisition of a color discrimination task.
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Affiliation(s)
- L J Fitten
- Psychiatry, Service, Veterans Administration Medical Center, Sepulveda, CA 91343
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Abstract
We treated 17 patients who had moderate to severe Alzheimer's disease with oral tetrahydroaminoacridine (THA), a centrally active anticholinesterase, in a three-phase study. In the nonblinded first phase of the study, significant improvement occurred in subjects who received the drug, as compared with their pretreatment status, on the global assessment (P = 0.001), the Orientation Test (P = 0.001), and the more sophisticated Names Learning Test (P = 0.001). During the second phase, the subjects served as their own controls in a double-blind, placebo-controlled, cross-over study in which the order of administration of the drug and placebo was randomly assigned. Among the 14 subjects completing Phase II, THA treatment produced significantly better results than placebo on the global assessment (P = 0.003), the Orientation Test (P = 0.004), the Alzheimer's Deficit Scale (P = 0.003), and the Names Learning Test (P = 0.001). Twelve subjects have entered Phase III, which involves long-term administration of oral THA. The average duration of treatment in these subjects at present is 12.6 months; symptomatic improvements have occurred, and no serious side effects attributable to THA have been observed. These encouraging initial results suggest that THA may be at least temporarily useful in the long-term palliative treatment of patients with Alzheimer's disease. We stress that further observations will be required before a clear assessment of the role of this agent can be made.
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Claus G, Kling A, Bolander K. Effects of methaqualone on social-sexual behavior in monkeys (M. mulatta) II. Simultaneously dosed subjects. Brain Behav Evol 1981; 18:105-13. [PMID: 7195761 DOI: 10.1159/000121780] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In a previous publication, we reported on the effects of 10 mg/kg i.m. injections of methaqualone on behavioral changes in treated animals and untreated members of a well-established colony of 10 rhesus monkeys (Macaca mulatta). The drug showed a biphasic effect, causing more passive behaviors in the first 80-100 min postinjection, followed by either aggression or increased sexual activity. After approximately 2 h, the social status and behavior of all animals returned to predrug levels. In general, affiliative activities increased under the influence of the drug, phenomena somewhat parallel tho those described among humans taking methaqualone in group settings. We also speculated that the drug may have an aphrodisiac potency. In the present experiments, 3 animals were caged together and injected simultaneously with the dose used earlier: an adult but naive male, who had been caged alone for infancy; an adult and subadult female, the 2 latter having had extensive social experience. After establishing baseline behaviors, five experiments with methaqualone were conducted, each lasting 2 h; and after the 2nd and 4th experiments, saline controls were carried out. There was a continuous increase from experiment to experiment in the affiliative behaviors of the animals; but during the saline trials, their behaviors returned nearly to those exhibited during baseline studies. Under the influence of methaqualone, the naive male attempted to copulate, which he achieved by the 4th drug trial; and at the same time he established his dominance. The conclusion was reached that methaqualone, indeed, has aphrodisiac potency, best measured by the time the male spent with erection under the influence of the drug, as compared with no erection during the baseline studies or the saline trials. The biphasic effect of methaqualone on behavior reported in the previous review [1] was also observed during the present experiments.
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