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121 results on '"Krauthamer, Victor"'

1. Strategic Considerations for Using Dietary Supplements in Austere Environments to Enhance Warfighter Readiness

Author

Currie, Tanisha L., Engler, Marguerite M., Krauthamer, Victor, Deuster, Patricia A., and Scott, Jonathan M.

Subjects
Mental health -- Analysis -- Research -- Health aspects, Antioxidants -- Research, Fruit -- Analysis -- Research -- Health aspects, Dietary supplements -- Analysis -- Research -- Health aspects, Food processing plants -- Health aspects -- Analysis -- Research, Isoflavones -- Analysis -- Research -- Health aspects, Health
Abstract

INTRODUCTION Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the United States (US) (1) and impacts approximately 18.1% of active-duty service members with at least one [...]

Published
2024

2. Biomechanical and functional variation in rat sciatic nerve following cuff electrode implantation

Author

Restaino, Stephen M, Abliz, Erkinay, Wachrathit, Kelliann, Krauthamer, Victor, and Shah, Sameer B

Subjects
Engineering, Biomedical Engineering, Neurosciences, Bioengineering, Assistive Technology, Rehabilitation, 2.1 Biological and endogenous factors, Aetiology, Animals, Biomechanical Phenomena, Electric Stimulation Therapy, Electrodes, Implanted, Electromyography, Male, Rats, Rats, Sprague-Dawley, Sciatic Nerve, Peripheral nerve, Cuff, Electrode, Electrophysiology, Biomechanics, EMG, Biomedical engineering
Abstract

BackgroundNerve cuff electrodes are commonly and successfully used for stimulating peripheral nerves. On the other hand, they occasionally induce functional and morphological changes following chronic implantation, for reasons not always clear. We hypothesize that restriction of nerve mobility due to cuff implantation may alter nerve conduction.MethodsWe quantified acute changes in nerve-muscle electrophysiology, using electromyography, and nerve kinematics in anesthetized Sprague Dawley rat sciatic nerves during controlled hindlimb joint movement. We compared electrophysiological and biomechanical response in uncuffed nerves and those secured within a cuff electrode using analysis of variance (ANOVA) and regression analysis.ResultsTethering resulting from cuff implantation resulted in altered nerve strain and a complex biomechanical environment during joint movement. Coincident with biomechanical changes, electromyography revealed significantly increased variability in the response of conduction latency and amplitude in cuffed, but not free, nerves following joint movement.ConclusionOur findings emphasize the importance of the mechanical interface between peripheral nerves and their devices on neurophysiological performance. This work has implications for nerve device design, implantation, and prediction of long-term efficacy.

Published
2014

14. Method for evaluating optical characteristics of endoscopes for recording fluorescence-related cardiac electrical activity

Author

Sau, Soma, Bassen, Howard I., and Krauthamer, Victor

Subjects
Endoscopes -- Evaluation, Colposcopes, Gastroscopes, Heart cells -- Measurement, Angioscopy -- Evaluation, Astronomy, Physics
Abstract

Nondestructive methods were used to evaluate marketed fiber-optic endoscopes (intended for simple viewing) for fluorescence recording. Our application is for optical recording from the heart. For one angioscope, we measured a focal length of 0.33 mm, a field of view of 45[degrees], an aperture of 0.26 mm, and an efficiency of 43%. We calculated that the angioscope would give a signal-to-noise ratio of 1.0 for a cardiac action potential, if its field of view were divided into a nine-pixel array (for safe continuous illumination). Our methods are useful in designing and evaluating fluorescence fiber-optic systems with superior signal quality and spatial resolution. OCIS codes: 170.2150, 170.4580, 260.2510, 170.5380

Published
2002

16. Two-point electrical-fluorescence recording from heart with optical fibers

Author

Krauthamer, Victor, Davis, Christopher C., and Gan, Ent-Syn

Subjects
Fiber optics -- Research, Signal processing -- Research, Cardiography -- Research, Biological sciences, Business, Computers, Health care industry
Abstract

Optical recordings from frog myocardium, stained with a voltage-sensitive dye, have been made through a fiber optic system that uses fiber couplers to provide two excitation/detection paths and to separate excitation light from the fluorescence signal. The excitation light, from a green He-Ne laser (543 nm), is focused into a 100 [[micro]meter]-core fiber then is split 1:1 to two other fibers. Each of these two fibers transmits part of the excitation light through a fiber coupler (1:15 transmittance ratio) to the heart preparation which is stained with the voltage-sensitive dye RH237. The returning red fluorescence is split at the same fiber coupler (15:1 transmittance ratio) and is directed to a photomultiplier tube through a longpass filter. With this two-point mapping method, differences in action potential shape and timing have been observed.

Published
1994

23. Development of a magneto-hydrodynamic solver for anatomical models

Author

Chang Isaac, Joel Myklebust, Nicolas Chavannes, Malisa Sarntinoranont, Niels Kuster, Wolfgang Kainz, Joshua Guag, S. Benkler, Jung Hwan Kim, and Krauthamer Victor

Subjects
Physics, Orientation (computer vision), Quantitative Biology::Tissues and Organs, Physics::Medical Physics, Measure (physics), Electronic engineering, Magnetohydrodynamics, Solver, Magnetostatics, Signal, Image resolution, Algorithm, Finite element method
Abstract

The developed MHD solver is able to calculate the induced current distribution and the equi-potentials in simple geometries. Preliminary validation of the MHD solver shows good agreement with values found in the literature [7] based on computational modeling. The implemented MHD solver is also able to calculate the induced fields in highly accurate models of the human anatomy. We will repeat the simulations in the future with an exact model of the geometry used in [7]. In addition we will perform an experimental validation to compare the MHD solver results with actual measurements. Future simulations will also include the calculation of the MHD signals for all four models of the Virtual Family. We will vary the orientation of the static magnetic field to maximize the MHD signal, and we will determine an optimized location for the measurement of the MHD signal. The optimal location for measuring the MHD signal is a location on the surface of the patient which maximizes the signal strength and optimizes the correlation of the MDH signal to the blood flow by minimizing the influence of the ECG signal. The volunteers based on which the Virtual Family models were developed (two adults and two children) will be used to measure the ECG signal and the combined ECG + MDH signal. The combined ECG + MDH will be measured inside a 3T MR scanner using an MR compatible ECG monitor. We will correlate the computational MHD results with the actual measurement. Based on this information we hope to develop a MHD based biomarker to non-invasively estimate the blood flow for the evaluation of heart failure.

Published
2009

47. FDA Regulation of Invasive Neural Recording Electrodes: A Daunting Task for Medical Innovators.

Author

Welle, Cristin and Krauthamer, Victor

Subjects
MEDICAL equipment, DRUG approval, ARTIFICIAL implants
Abstract

The U.S. Food and Drug Administration (FDA) is charged with assuring the safety and effectiveness of medical devices. Before any medical device can be brought to market, it must comply with all federal regulations regarding FDA processes for clearance or approval. Navigating the FDA regulatory process may seem like a daunting task to the innovator of a novel medical device who has little experience with the FDA regulatory process or device commercialization. This review introduces the basics of the FDA regulatory premarket process, with a focus on issues relating to chronically implanted recording devices in the central or peripheral nervous system. Topics of device classification and regulatory pathways, the use of standards and guidance documents, and optimal time lines for interaction with the FDA are discussed. Additionally, this article summarizes the regulatory research on neural implant safety and reliability conducted by the FDA's Office of Science and Engineering Laboratories (OSEL) in collaboration with Defense Advanced Research Projects Agency (DARPA) Reliable Neural Technology (RE-NET) Program. For a more detailed explanation of the medical device regulatory process, please refer to several excellent reviews of the FDA's regulatory pathways for medical devices [1][4].. [ABSTRACT FROM PUBLISHER]

Published
2012
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49. Ray-tracing study on the post-scanner variable beam expansion optics in a two-photon microscopy system

Author

Kim, Do-Hyun, Welle, Cristin, and Krauthamer, Victor

Abstract

Due to the low signal levels typical of two-photon microscopy (TPM) in biological samples, optical design optimization is critical. One of the most important factors is overfilling of the back aperture of the objective lens. A variable beam expander is commonly placed before the scanning mirrors to achieve this goal, however, this may cause degradation of image quality due to increased dispersion. Additionally, scanning mirror size restricts the degree of expansion, which often prevents the overfilling of objective lens back aperture. We investigated the implementation of variable beam expansion optics after the scanning mirrors. Ray-tracing analyses confirmed that the post-scanner beam expansion has two key advantages over the conventional pre-scanner beam expansion approach: decreasing the number of optical elements reduces pulse dispersion and reducing the size of the scanning mirror enables faster scanning. Resolution and aberration of a TPM with post-scanner beam expansion optics were analysed.

Published
2012
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50. Optical method of recording electrical activity in isolated rabbit hearts

Author

Amanna, Ashwin E., Electrical Engineering, Wang, Anbo, Krauthamer, Victor, and Reed, Jeffrey H.

Subjects
Endoscopes, LD5655.V855 1993.A445, sense organs
Abstract

A recently developed optical method utilizes a single, implantable, optical fiber to record electrical activity from isolated hearts stained with voltage-sensitive dyes. This optical technique generates recordings of transmembrane potential from excitable myocardial tissue, and remain free from stimulus artifacts that accompany electro stimulation and hinder all standard electrode recording methods during the application of high-voltage electrical shocks. The fiber optic system uses a l00J,lm diameter core fiber which can record from epicardial surface, internal mid-myocardium, or endocardial surfaces. The stained tissue is excited through the fiber and the resulting fluorescence is transmitted through the same fiber to a photomultiplier tube. Changes in fluorescence accompanying normal cardiac action potentials usually range from 1-5%. Substantive motion related signals accompany normal beating hearts, drowning out the actual signal that corresponds to change in membrane potential. When added to the nutrient solution of the heart, an excitation / contraction decoupler restricts motion and reduces the motion related signal making it easier to isolate the true membrane potential signal. Master of Science

Published
1993

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