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Williams CL, Ponganis PJ. Diving physiology of marine mammals and birds: the development of biologging techniques. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200211. [PMID: 34121464 PMCID: PMC8200650 DOI: 10.1098/rstb.2020.0211] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/14/2021] [Indexed: 11/12/2022] Open
Abstract
In the 1940s, Scholander and Irving revealed fundamental physiological responses to forced diving of marine mammals and birds, setting the stage for the study of diving physiology. Since then, diving physiology research has moved from the laboratory to the field. Modern biologging, with the development of microprocessor technology, recorder memory capacity and battery life, has advanced and expanded investigations of the diving physiology of marine mammals and birds. This review describes a brief history of the start of field diving physiology investigations, including the invention of the time depth recorder, and then tracks the use of biologging studies in four key diving physiology topics: heart rate, blood flow, body temperature and oxygen store management. Investigations of diving heart rates in cetaceans and O2 store management in diving emperor penguins are highlighted to emphasize the value of diving physiology biologging research. The review concludes with current challenges, remaining diving physiology questions and what technologies are needed to advance the field. This article is part of the theme issue 'Measuring physiology in free-living animals (Part I)'.
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Affiliation(s)
- Cassondra L. Williams
- National Marine Mammal Foundation, 2240 Shelter Island Drive, Suite 200, San Diego, CA 92106, USA
| | - Paul J. Ponganis
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0204, USA
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2
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Williams CL, Hindle AG. Field Physiology: Studying Organismal Function in the Natural Environment. Compr Physiol 2021; 11:1979-2015. [PMID: 34190338 DOI: 10.1002/cphy.c200005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Continuous physiological measurements collected in field settings are essential to understand baseline, free-ranging physiology, physiological range and variability, and the physiological responses of organisms to disturbances. This article presents a current summary of the available technologies to continuously measure the direct physiological parameters in the field at high-resolution/instantaneous timescales from freely behaving animals. There is a particular focus on advantages versus disadvantages of available methods as well as emerging technologies "on the horizon" that may have been validated in captive or laboratory-based scenarios but have yet to be applied in the wild. Systems to record physiological variables from free-ranging animals are reviewed, including radio (VHF/UFH) telemetry, acoustic telemetry, and dataloggers. Physiological parameters that have been continuously measured in the field are addressed in seven sections including heart rate and electrocardiography (ECG); electromyography (EMG); electroencephalography (EEG); body temperature; respiratory, blood, and muscle oxygen; gastric pH and motility; and blood pressure and flow. The primary focal sections are heart rate and temperature as these can be, and have been, extensively studied in free-ranging organisms. Predicted aspects of future innovation in physiological monitoring are also discussed. The article concludes with an overview of best practices and points to consider regarding experimental designs, cautions, and effects on animals. © 2021 American Physiological Society. Compr Physiol 11:1979-2015, 2021.
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Affiliation(s)
- Cassondra L Williams
- National Marine Mammal Foundation, San Diego, California, USA.,Department of Ecology and Evolutionary Biology, School of Biological Science, University of California Irvine, Irvine, California, USA
| | - Allyson G Hindle
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, USA
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3
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Bøgh N, Agger P, Omann C, Skov MN, Laustsen C, Wang T, Pedersen M. New Device for Noninvasive Telemetric Monitoring of Vital Signs in Healthy and Newly Operated Piglets. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE 2019; 59:90-93. [PMID: 31806077 DOI: 10.30802/aalas-jaalas-19-000052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Measuring vital signs is central to medical practice, but they are difficult to monitor in awake laboratory animals. We examined the feasibility of a noninvasive device for telemetric assessment of respiration rate, heart rate, temperature and movement in pigs. Awake piglets were monitored continuously for 31 h (interquartile range, 7) before (n = 4) and after (n = 3) surgery. Data quality was sufficient for determination of all parameters. We conclude that continuous, noninvasive monitor- ing of pigs is possible by using the evaluated device.
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Koch J, Schuettler M, Pasluosta C, Stieglitz T. Electrical connectors for neural implants: design, state of the art and future challenges of an underestimated component. J Neural Eng 2019; 16:061002. [PMID: 31362277 DOI: 10.1088/1741-2552/ab36df] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Technological advances in electrically active implantable devices have increased the complexity of hardware design. In particular, the increasing number of stimulation and recording channels requires innovative approaches for connectors that interface electrodes with the implant circuitry. OBJECTIVE This work aims to provide a common theoretical ground for implantable connector development with a focus on neural applications. APPROACH Aspects and experiences from several disciplines are compiled from an engineering perspective to discuss the state of the art of connector solutions. Whenever available, we also present general design guidelines. MAIN RESULTS Degradation mechanisms, material stability and design rules in terms of biocompatibility and biostability are introduced. Considering contact physics, we address the design and characterization of the contact zone and review contaminants, wear and contact degradation. For high-channel counts and body-like environments, insulation can be even more crucial than the electrical connection itself. Therefore, we also introduce the requirements for electrical insulation to prevent signal loss and distortion and discuss its impact on the practical implementation. SIGNIFICANCE A final review is dedicated to the state of the art connector concepts, their mechanical setup, electrical performance and the interface to other implant components. We conclude with an outlook for possible approaches for the future generations of implants.
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Affiliation(s)
- Julia Koch
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany
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Remote physiological monitoring provides unique insights on the cardiovascular performance and stress responses of freely swimming rainbow trout in aquaculture. Sci Rep 2019; 9:9090. [PMID: 31235773 PMCID: PMC6591390 DOI: 10.1038/s41598-019-45657-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Accepted: 06/12/2019] [Indexed: 02/06/2023] Open
Abstract
Investigating the mechanisms that fish employ to maintain homeostasis in their everyday life requires measurements of physiological and behavioural responses in the field. With multivariate bio-loggers, we continuously measured gastrointestinal blood flow (GBF), heart rate, activity and body temperature in rainbow trout (Oncorhynchus mykiss) swimming freely amongst ~5000 conspecifics in a sea cage. Our findings clearly demonstrate that while both acute aquaculture-related stress and spontaneous activity resulted in transient reductions in GBF (i.e. reductions of up to 65%), recovery from stressful handling practices subsequently involved a substantial and prolonged gastrointestinal hyperemia far beyond the level observed prior to the stressor. The gastrointestinal hyperemia may be necessary to repair the damage to the gastrointestinal tract caused by acute stress. Furthermore, heart rate responses to acute stress or voluntary activity differed depending on the individual’s physiological state. Stressed fish (i.e. mean heart rates >70 beats min−1) exhibited a bradycardic response to acute stress or activity, whereas fish with mean heart rates <60 beats min−1 instead demonstrated strong tachycardic responses. Remote monitoring of physiological and behavioural variables using bio-loggers can provide unique insights into ‘real-life’ responses of animals, which can largely differ from the responses observed in confined laboratory settings.
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Joyce W, Crossley J, Elsey RM, Wang T, Crossley DA. Contribution of active atrial contraction to cardiac output in anesthetized American alligators ( Alligator mississippiensis). ACTA ACUST UNITED AC 2018; 221:jeb.178194. [PMID: 29615521 DOI: 10.1242/jeb.178194] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 03/21/2018] [Indexed: 12/30/2022]
Abstract
Ventricular filling may occur directly from the venous circulation during early diastole or via atrial contraction in late diastole. The contribution of atrial contraction to ventricular filling is typically small in mammals (10-40%), but has been suggested to predominate in reptiles. We investigated the importance of atrial contraction in filling of the ventricle in American alligators (Alligator mississippiensis) by bypassing both atria (with the use of ligatures to prevent atrial filling) and measuring the resultant effects on cardiac output in anesthetized animals. Atrial ligation had no significant effects on total systemic blood flow before or after adrenaline injection. Unexpectedly, pulmonary flow was increased following atrial ligation prior to adrenaline treatment, but was unaffected after it. These findings suggest that the atria are non-essential (i.e. redundant) for ventricular filling in alligators, at least under anesthesia, but may serve as important volume reservoirs.
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Affiliation(s)
- William Joyce
- Department of Zoophysiology, Aarhus University, 8000 Aarhus C, Denmark
| | - Janna Crossley
- Department of Biological Sciences, Developmental Integrative Biology Cluster, University of North Texas, Denton, TX 76203-5017, USA
| | - Ruth M Elsey
- Louisiana Department of Wildlife and Fisheries, Rockefeller Wildlife Refuge, Grand Chenier, LA 70643, USA
| | - Tobias Wang
- Department of Zoophysiology, Aarhus University, 8000 Aarhus C, Denmark.,Aarhus Institute of Advanced Studies, Aarhus University, 8000 Aarhus C, Denmark
| | - Dane A Crossley
- Department of Biological Sciences, Developmental Integrative Biology Cluster, University of North Texas, Denton, TX 76203-5017, USA
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Body temperature and motion: Evaluation of an online monitoring system in pigs challenged with Porcine Reproductive & Respiratory Syndrome Virus. Res Vet Sci 2017; 114:482-488. [DOI: 10.1016/j.rvsc.2017.09.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 08/14/2017] [Accepted: 09/22/2017] [Indexed: 11/15/2022]
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Rothfuss MA, Unadkat JV, Gimbel ML, Mickle MH, Sejdić E. Totally Implantable Wireless Ultrasonic Doppler Blood Flowmeters: Toward Accurate Miniaturized Chronic Monitors. ULTRASOUND IN MEDICINE & BIOLOGY 2017; 43:561-578. [PMID: 28038789 DOI: 10.1016/j.ultrasmedbio.2016.11.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 10/27/2016] [Accepted: 11/12/2016] [Indexed: 06/06/2023]
Abstract
Totally implantable wireless ultrasonic blood flowmeters provide direct-access chronic vessel monitoring in hard-to-reach places without using wired bedside monitors or imaging equipment. Although wireless implantable Doppler devices are accurate for most applications, device size and implant lifetime remain vastly underdeveloped. We review past and current approaches to miniaturization and implant lifetime extension for wireless implantable Doppler devices and propose approaches to reduce device size and maximize implant lifetime for the next generation of devices. Additionally, we review current and past approaches to accurate blood flow measurements. This review points toward relying on increased levels of monolithic customization and integration to reduce size. Meanwhile, recommendations to maximize implant lifetime should include alternative sources of power, such as transcutaneous wireless power, that stand to extend lifetime indefinitely. Coupling together the results will pave the way for ultra-miniaturized totally implantable wireless blood flow monitors for truly chronic implantation.
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Affiliation(s)
- Michael A Rothfuss
- Department of Electrical and Computer Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Jignesh V Unadkat
- Department of Plastic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Michael L Gimbel
- Department of Plastic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Marlin H Mickle
- Department of Electrical and Computer Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Ervin Sejdić
- Department of Electrical and Computer Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
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Affiliation(s)
- James E. Bogan
- The Critter Fixer of Central Florida, LLC, 83 Geneva Drive, 621679, Oviedo, FL 32765, USA
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10
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Cooke SJ, Brownscombe JW, Raby GD, Broell F, Hinch SG, Clark TD, Semmens JM. Remote bioenergetics measurements in wild fish: Opportunities and challenges. Comp Biochem Physiol A Mol Integr Physiol 2016; 202:23-37. [PMID: 27063208 DOI: 10.1016/j.cbpa.2016.03.022] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/08/2016] [Accepted: 03/31/2016] [Indexed: 10/22/2022]
Abstract
The generalized energy budget for fish (i.e., Energy Consumed=Metabolism+Waste+Growth) is as relevant today as when it was first proposed decades ago and serves as a foundational concept in fish biology. Yet, generating accurate measurements of components of the bioenergetics equation in wild fish is a major challenge. How often does a fish eat and what does it consume? How much energy is expended on locomotion? How do human-induced stressors influence energy acquisition and expenditure? Generating answers to these questions is important to fisheries management and to our understanding of adaptation and evolutionary processes. The advent of electronic tags (transmitters and data loggers) has provided biologists with improved opportunities to understand bioenergetics in wild fish. Here, we review the growing diversity of electronic tags with a focus on sensor-equipped devices that are commercially available (e.g., heart rate/electrocardiogram, electromyogram, acceleration, image capture). Next, we discuss each component of the bioenergetics model, recognizing that most research to date has focused on quantifying the activity component of metabolism, and identify ways in which the other, less studied components (e.g., consumption, specific dynamic action component of metabolism, somatic growth, reproductive investment, waste) could be estimated remotely. We conclude with a critical but forward-looking appraisal of the opportunities and challenges in using existing and emerging electronic sensor-tags for the study of fish energetics in the wild. Electronic tagging has become a central and widespread tool in fish ecology and fisheries management; the growing and increasingly affordable toolbox of sensor tags will ensure this trend continues, which will lead to major advances in our understanding of fish biology over the coming decades.
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Affiliation(s)
- Steven J Cooke
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, 1125 Colonel By Dr., Ottawa, ON, K1S 5B6, Canada.
| | - Jacob W Brownscombe
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, 1125 Colonel By Dr., Ottawa, ON, K1S 5B6, Canada
| | - Graham D Raby
- Great Lakes Institute of Environmental Research, University of Windsor, 401 Sunset Ave., Windsor, ON, N9B 3P4, Canada
| | - Franziska Broell
- Department of Oceanography, Dalhousie University, 1355 Oxford St., Halifax, NS, B3H 4R2, Canada
| | - Scott G Hinch
- Department of Forest & Conservation Sciences, University of British Columbia, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada
| | - Timothy D Clark
- University of Tasmania and CSIRO Agriculture Flagship, 3-4 Castray Esplanade, Hobart, TAS 7000, Australia
| | - Jayson M Semmens
- Fisheries and Aquaculture Centre, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7001, Australia
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11
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In Vivo Wireless Monitoring System of Cardiovascular Force Data. Cardiovasc Eng Technol 2014; 6:2-7. [PMID: 26577097 DOI: 10.1007/s13239-014-0207-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 11/28/2014] [Indexed: 10/24/2022]
Abstract
Biotelemetry provides the possibility to measure physiological data in awake, free-ranging animals without the effects of anesthesia and repeated surgery. In this project a fully implantable, telemetric system to measure biomechanical force data of the moving structures of the heart along with the ECG of experimental animals was developed. The system is based on a microcontroller with a built in bidirectional radio frequency transceiver, which allows for the implant to both receive and send data wirelessly. ECG was acquired using electrodes placed directly onto the heart, and the forces were collected using a miniature force transducer. The system was tested in a porcine model (60 kg body weight), where the system transmitted ECG and force data at a range of 5 m between the implant and the receiver. The data was displayed and saved to the hard drive of a laptop computer using a custom built software user interface. It was shown feasible to wirelessly measure forces simultaneously with physiological data from the cardiovascular system of living animals. The current system was optimized to measure forces and ECG, and more channels can be added to increase the number of parameters recorded.
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Choy JS, Zhang ZD, Pitsillides K, Sosa M, Kassab GS. Longitudinal hemodynamic measurements in swine heart failure using a fully implantable telemetry system. PLoS One 2014; 9:e103331. [PMID: 25119289 PMCID: PMC4131878 DOI: 10.1371/journal.pone.0103331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 07/01/2014] [Indexed: 11/19/2022] Open
Abstract
Chronic monitoring of heart rate, blood pressure, and flow in conscious free-roaming large animals can offer considerable opportunity to understand the progression of cardiovascular diseases and can test new diagnostics and therapeutics. The objective of this study was to demonstrate the feasibility of chronic, simultaneous measurement of several hemodynamic parameters (left ventricular pressure, systemic pressure, blood flow velocity, and heart rate) using a totally implantable multichannel telemetry system in swine heart failure models. Two solid-state blood pressure sensors were inserted in the left ventricle and the descending aorta for pressure measurements. Two Doppler probes were placed around the left anterior descending (LAD) and the brachiocephalic arteries for blood flow velocity measurements. Electrocardiographic (ECG) electrodes were attached to the surface of the left ventricle to monitor heart rate. The telemeter body was implanted in the right side of the abdomen under the skin for approximately 4 to 6 weeks. The animals were subjected to various heart failure models, including volume overload (A-V fistula, n = 3), pressure overload (aortic banding, n = 2) and dilated cardiomyopathy (pacing-induced tachycardia, n = 3). Longitudinal changes in hemodynamics were monitored during the progression of the disease. In the pacing-induced tachycardia animals, the systemic blood pressure progressively decreased within the first 2 weeks and returned to baseline levels thereafter. In the aortic banding animals, the pressure progressively increased during the development of the disease. The pressure in the A-V fistula animals only showed a small increase during the first week and remained stable thereafter. The results demonstrated the ability of this telemetry system of long-term, simultaneous monitoring of blood flow, pressure and heart rate in heart failure models, which may offer significant utility for understanding cardiovascular disease progression and treatment.
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Affiliation(s)
- Jenny S. Choy
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | - Zhen-Du Zhang
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | | | - Margo Sosa
- Transonic Systems Inc., Ithaca, New York, United States of America
| | - Ghassan S. Kassab
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis, Indiana, United States of America
- Department of Surgery, Indiana University, Indianapolis, Indiana, United States of America
- Department of Cellular and Integrative Physiology, Indiana University, Indianapolis, Indiana, United States of America
- * E-mail:
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Gardner MN, Sterba-Boatwright B, Jones DR. Ligation of the left aorta in alligators affects acid–base balance: A role for the R→L shunt. Respir Physiol Neurobiol 2011; 178:315-22. [DOI: 10.1016/j.resp.2011.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 06/30/2011] [Accepted: 07/01/2011] [Indexed: 11/25/2022]
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Elucidating the responses and role of the cardiovascular system in crocodilians during diving: Fifty years on from the work of C.G. Wilber. Comp Biochem Physiol A Mol Integr Physiol 2011; 160:1-8. [DOI: 10.1016/j.cbpa.2011.05.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 04/27/2011] [Accepted: 05/17/2011] [Indexed: 11/18/2022]
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Chinnadurai SK, DeVoe R, Koenig A, Gadsen N, Ardente A, Divers SJ. Comparison of an implantable telemetry device and an oscillometric monitor for measurement of blood pressure in anaesthetized and unrestrained green iguanas (Iguana iguana). Vet Anaesth Analg 2010; 37:434-9. [DOI: 10.1111/j.1467-2995.2010.00557.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Lohse L, Uttenthal Å, Enøe C, Nielsen J. A study on the applicability of implantable microchip transponders for body temperature measurements in pigs. Acta Vet Scand 2010; 52:29. [PMID: 20444254 PMCID: PMC2881076 DOI: 10.1186/1751-0147-52-29] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 05/05/2010] [Indexed: 01/21/2023] Open
Abstract
Background The applicability of an electronic monitoring system using microchip transponders for measurement of body temperatures was tested in 6-week-old conventional Danish weaners infected with classical swine fever virus (CSFV). Subcutaneous tissue temperatures obtained by the implantable transponders were compared with rectal temperatures, recorded by a conventional digital thermometer. Methods In a preliminary study, transponders were inserted subcutaneously at 6 different positions of the body of 5 pigs. The transponders positioned by the ear base provided the best correlation to rectal temperature. To test the stability of the monitoring system in a larger group of pigs, transponders were therefore inserted by the left ear base in a subsequent infection experiment with 30 pigs. Results Generally, the microchip transponders measured a subcutaneous tissue temperature, which was about 1°C lower than the rectal temperature. However, a simple linear relationship between the measures of the two methods was found. Conclusions Our study showed that the tested body monitoring system may represent a promising tool to obtain an approximate correlate of body temperatures in groups of pigs. In contrast, however, the tested system did not constitute a suitable tool to measure body temperatures of individual animals in the present pig infection experiment.
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Abstract
Remodeling of tissue in response to physical stress is a very complex process. The changes in the stimulus (cause) and response (effect) must be measured and the results must be organized into mathematical forms that are suitable for predictions and applications. An experiment where the stimulus (pressure, flow, shear stress, etc.) can be changed approximately as a step function (a step plus a perturbation) and the response (structure, material properties, function, etc.), which can be measured over time, can be simulated by indicial response functions (IRFs). The IRF is a mathematical expression of the ratio of the change in a particular feature of the system in response to a unit step change in stimulus. The IRF approach provides a quantitative description of the remodeling process, simplifies the interpretation of data, and greatly increases the potential of using the experimental data for prediction of the outcome for future experiments. The objective of this review is to provide an overview of the IRF approach including some exemplary systems. The goal is to illustrate how the indicial expressions make it possible to integrate biological complexity by convolution. The time courses of stimuli represent half of the convolution while the time course of changes in response represents the second half of the convolution. The IRF approach provides an understanding of the physiological problems with mathematical accuracy and may be conducive to new findings.
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Affiliation(s)
- Ghassan S Kassab
- Department of Biomedical Engineering, IUPUI, Indianapolis, IN 46202, USA.
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18
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Jones D, Gardner M. Ring around the heart: an unusual feature of the crocodilian central circulatory system. ACTA ACUST UNITED AC 2010. [DOI: 10.7882/az.2010.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Brøndum E, Hasenkam JM, Secher NH, Bertelsen MF, Grøndahl C, Petersen KK, Buhl R, Aalkjær C, Baandrup U, Nygaard H, Smerup M, Stegmann F, Sloth E, Østergaard KH, Nissen P, Runge M, Pitsillides K, Wang T. Jugular venous pooling during lowering of the head affects blood pressure of the anesthetized giraffe. Am J Physiol Regul Integr Comp Physiol 2009; 297:R1058-65. [DOI: 10.1152/ajpregu.90804.2008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
How blood flow and pressure to the giraffe's brain are regulated when drinking remains debated. We measured simultaneous blood flow, pressure, and cross-sectional area in the carotid artery and jugular vein of five anesthetized and spontaneously breathing giraffes. The giraffes were suspended in the upright position so that we could lower the head. In the upright position, mean arterial pressure (MAP) was 193 ± 11 mmHg (mean ± SE), carotid flow was 0.7 ± 0.2 l/min, and carotid cross-sectional area was 0.85 ± 0.04 cm2. Central venous pressure (CVP) was 4 ± 2 mmHg, jugular flow was 0.7 ± 0.2 l/min, and jugular cross-sectional area was 0.14 ± 0.04 cm2 ( n = 4). Carotid arterial and jugular venous pressures at head level were 118 ± 9 and −7 ± 4 mmHg, respectively. When the head was lowered, MAP decreased to 131 ± 13 mmHg, while carotid cross-sectional area and flow remained unchanged. Cardiac output was reduced by 30%, CVP decreased to −1 ± 2 mmHg ( P < 0.01), and jugular flow ceased as the jugular cross-sectional area increased to 3.2 ± 0.6 cm2 ( P < 0.01), corresponding to accumulation of ∼1.2 l of blood in the veins. When the head was raised, the jugular veins collapsed and blood was returned to the central circulation, and CVP and cardiac output were restored. The results demonstrate that in the upright-positioned, anesthetized giraffe cerebral blood flow is governed by arterial pressure without support of a siphon mechanism and that when the head is lowered, blood accumulates in the vein, affecting MAP.
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Affiliation(s)
| | - J. M. Hasenkam
- Institute of Clinical Medicine, Departments of CardioThoracic and Vascular Surgery, and
| | | | - M. F. Bertelsen
- Department of Large Animal Science, University of Copenhagen, and
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Copenhagen, Denmark
| | - C. Grøndahl
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Copenhagen, Denmark
| | | | - R. Buhl
- Department of Large Animal Science, University of Copenhagen, and
| | | | - U. Baandrup
- Institute of Pathology, Aarhus University Hospital, Aarhus, Denmark
- Vendsyssel Hospital, Hjørring, Denmark
| | - H. Nygaard
- Institute of Clinical Medicine, Departments of CardioThoracic and Vascular Surgery, and
- Engineering College of Aarhus, Aarhus, Denmark
| | - M. Smerup
- Institute of Clinical Medicine, Departments of CardioThoracic and Vascular Surgery, and
| | - F. Stegmann
- Department of Companion Animal Clinical Studies, University of Pretoria, Pretoria, South Africa; and
| | - E. Sloth
- Institute of Clinical Medicine, Departments of CardioThoracic and Vascular Surgery, and
| | | | - P. Nissen
- Department of Anesthesiology, Rigshospitalet,
| | - M. Runge
- Department of Anesthesiology, Rigshospitalet,
| | | | - T. Wang
- Zoophysiology, Department of Biological Sciences, Aarhus University, Aarhus, Denmark
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A comparative analysis of coronary and aortic flow waveforms. Ann Biomed Eng 2008; 36:933-46. [PMID: 18398682 DOI: 10.1007/s10439-008-9488-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2007] [Accepted: 03/24/2008] [Indexed: 10/22/2022]
Abstract
Empirical Mode decomposition (EMD) is a mathematical tool designed to analyze non-stationary, non-linear stochastic waves. EMD separates a waveform into its constituent modes of oscillations or intrinsic mode functions (IMFs) and provides meaningful definitions of instantaneous frequency, instantaneous energy, mean trends and oscillation about the mean trends. This study provides a detailed mathematical analysis of blood flow waveforms in the porcine left anterior descending artery and aorta using EMD. Flow data with non-stationary and non-linear characteristics were obtained for several hours using an implanted wireless biotelemetry device. EMD was validated against modern numerical techniques of principal component analysis (PCA) and wavelet analysis by comparing their predicted mean trends and energy distribution. EMD has an advantage over both techniques since it combines the strengths of both: it is adaptive (similar to PCA), and it can define instantaneous frequencies (similar to wavelet analysis). Because of the iterative nature, however, calculations using EMD can be computationally intensive. Sampling rate reduction was used to reduce computation time, without significantly effecting accuracy of IMF calculations. It was found that IMFs calculated at a sampling rate as low as 20 Hz were not significantly different (<6%) from those obtained at the original sampling rate (200 Hz). Our findings suggest that EMD may be a powerful mathematical tool to characterize flow waveforms.
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Huo Y, Wischgoll T, Kassab GS. Flow patterns in three-dimensional porcine epicardial coronary arterial tree. Am J Physiol Heart Circ Physiol 2007; 293:H2959-70. [PMID: 17827262 DOI: 10.1152/ajpheart.00586.2007] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The branching pattern of epicardial coronary arteries is clearly three-dimensional, with correspondingly complex flow patterns. The objective of the present study was to perform a detailed hemodynamic analysis using a three-dimensional finite element method in a left anterior descending (LAD) epicardial arterial tree, including main trunk and primary branches, based on computed tomography scans. The inlet LAD flow velocity was measured in an anesthetized pig, and the outlet pressure boundary condition was estimated based on scaling laws. The spatial and temporal wall shear stress (WSS), gradient of WSS (WSSG), and oscillatory shear index (OSI) were calculated and used to identify regions of flow disturbances in the vicinity of primary bifurcations. We found that low WSS and high OSI coincide with disturbed flows (stagnated, secondary, and reversed flows) opposite to the flow divider and lateral to the junction orifice of the main trunk and primary branches. High time-averaged WSSG occurs in regions of bifurcations, with the flow divider having maximum values. Low WSS and high OSI were found to be related through a power law relationship. Furthermore, zones of low time-averaged WSS and high OSI amplified for larger diameter ratio and high inlet flow rate. Hence, different focal atherosclerotic-prone regions may be explained by different physical mechanism associated with certain critical levels of low WSS, high OSI, and high WSSG, which are strongly affected by the diameter ratio. The implications of the flow patterns for atherogenesis are enumerated.
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Affiliation(s)
- Yunlong Huo
- Department of Biomedical Engineering, Indiana University Purdue University, Indianapolis, IN 46202, USA
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