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PubMed2005

Sensitivity of the anterior lateral line to natural stimuli in the oyster toadfish, Opsanus tau (Linnaeus).

Inductive neural telemetry was used to record from microwire electrodes chronically implanted into the anterior lateral line nerve of the oyster toadfish, Opsanus tau (L.). The lateral lines of free-ranging toadfish were stimulated by the swimming movements of a prey fish (Fundulus heteroclitus), and the corresponding neural activity was quantified. Both spontaneously active and silent afferent fibers experienced an increase in neural firing as the prey approached the lateral line. Activity was evoked when the prey fish approached to within 8-12 cm of the neuromast, with increases in nerve firing rates directly correlated with diminishing distance. Thus, adult toadfish (28 cm standard length; 33 cm total length) were only able to detect mobile prey that approached within approximately 40% of their body length. Both spontaneously active and silent afferent fibers also experienced a dramatic increase in firing during predatory strikes, indicating that the fibers were not inhibited during rapid body movement. This study investigates, for the first time, the neural response of the anterior lateral line to prey stimuli in free-ranging fish.

Analysis of Variance↗

PubMed2006

Identifying and quantifying prey consumption using stomach temperature change in pinnipeds.

For many marine predators knowledge of foraging behavior is limited to inferences based on changes in diving or movement patterns at sea. This results in an incomplete and potentially inaccurate view of the foraging ecology of a species. This study examined the use of stomach temperature telemetry to identify and quantify prey consumed in both a phocid (northern elephant seal Mirounga angustirostris) and an otariid (California sea lion Zalophus californianus) species. In addition, we used opportunistic water consumption by northern elephant seals to test a method to distinguish between prey and water ingestion. Over 96% of feedings could be identified based on a decline in stomach temperature, even when meals were separated by as little as 70 min. Water consumption was distinguishable from prey consumption, as the rate of recovery in stomach temperature was significantly faster for water (F(1,142) = 79.2, P < 0.01). However, using this method, the overlap in recovery rates between prey and water resulted in 30.6% of water ingestion events being misclassified as prey ingestion. For both species, the integral calculated from the decline in stomach temperature over time (area above the curve) could be used to estimate mass consumed, when adjusted for the temperature difference between the prey and core body temperature. For California sea lions, there was a significant effect of individual on the ability to quantify prey consumed, which was not related to their mass or sex. Although many factors may influence the ability to use stomach temperature change to identify and quantify prey consumed, this study has shown measures of stomach temperature can accurately identify prey consumption and provide an estimate of meal mass, allowing for a greater understanding of the feeding behavior of marine mammals.

Animals↗

PubMed1992

Ultrasonic vocalizations of flying bats monitored by radiotelemetry.

Ultrasonic vocalizations of flying bats were effectively monitored with radiotelemetry. We describe a device light enough to be carried by an 11 g bat for periods of up to 1 h. It transmitted signals adequate for fine frequency analysis within a range of approximately 3 m. Telemetry permitted the recording of constant-frequency pulses free from flight-induced Doppler shifts and without time delays. The difference in frequency between telemetered signals and the same signals detected by a remote microphone was used to calculate velocity and Doppler shifts. Pulse emission behavior of Pteronotus parnellii in flight was compared with simulated flight on a pendulum. The data showed significant differences in echo bandwidths, constant-frequency pulse durations and interpulse intervals. In flight, pulses and interpulse intervals tended to be shorter and bats maintained echo frequencies within a significantly narrower band. Phases of echolocation that characterized the approach to a target were clearly evident in flight, but not during pendulum swings. Differences in pulse durations and interpulse intervals may be correlated with the integration of wingbeat, respiration and vocalization. The absence of wing motion in simulated flight changes this integration.

Animals↗

PubMed1994

Evaluation of the long-lasting antihypertensive action of 7-O-ethylfangchinoline.

The antihypertensive effect of 7-O-ethylfangchinoline (TJN-220) was analyzed in an experimental model of hypertensive rats under the conscious condition. Single oral administration of TJN-220 (25 and 50 mg/kg) produced a progressive and long-lasting fall of mean blood pressure in spontaneously hypertensive rats (SHRs), deoxycorticosterone acetate (DOCA)-salt hypertensive rats and renal hypertensive rats until 72 hr after the drug administration, but affected neither the heart rate in these hypertensive rats nor the hemodynamic parameters in normotensive rats. In SHRs implanted with a telemetry transmitter, TJN-220 (50 mg/kg, p.o.) produced falls of systolic and diastolic blood pressures and diminished the difference in blood pressure between the dark period and the light period for 3 days, particularly by suppressing the increasing phase of blood pressure during the dark period without influencing heart rate or locomotor activity. On the other hand, nicardipine (10 mg/kg, p.o.) produced a transient fall of blood pressure associated with a tachycardia during the light period on the first day alone. Clonidine (0.3 mg/kg, p.o.) diminished the increasing phases of blood pressure and heart rate during the dark period on the first day alone. Thus, the antihypertensive action of TJN-220 was much longer than those of nicardipine and clonidine. The present results suggest that TJN-220 may have potential for use as a beneficial antihypertensive drug.

Alkaloids↗

PubMed2005

QT PRODACT: in vivo QT assay in the conscious dog for assessing the potential for QT interval prolongation by human pharmaceuticals.

The goal of the present study was to examine the utility of the conscious dog model by assessing the QT-interval-prolonging potential of ten positive compounds that have been reported to induce QT interval prolongation in clinical use and seven negative compounds considered not to have such an effect. Three doses of test compounds or vehicle were administered orally to male beagle dogs (n=4), and telemetry signals were recorded for 24 h after administration. All positive compounds (astemizole, bepridil, cisapride, E-4031, haloperidol, MK-499, pimozide, quinidine, terfenadine, and thioridazine) caused a significant increase in the corrected QT (QTc) interval, with a greater than 10% increase achieved at high doses. In contrast, administration of negative compounds (amoxicillin, captopril, ciprofloxacin, diphenhydramine, nifedipine, propranolol, and verapamil) did not produce any significant change in the QTc interval, with the exception of nifedipine that may have produced an overcorrection of the QTc interval due to increased heart rate. The estimated plasma concentrations of the positive compounds that caused a 10% increase in the QTc interval were in good agreement with the plasma/serum concentrations achieved in humans who developed prolonged QT interval or torsade de pointes (TdP). Although careful consideration should be given to the interpretation of QT data with marked heart rate change, these data suggest that an in vivo QT assay using the conscious dog is a useful model for the assessment of QT interval prolongation by human pharmaceuticals.

Animals↗

PubMed2003

The impact of low levels of carbon dioxide on rats.

The widespread use of individually ventilated cage (IVC) systems today has made the impact of CO(2) on rodents a highly important matter. Leaving cages from these systems without ventilation increases CO(2) concentrations inside the cages, as CO(2) generated from the animals is no longer removed actively. In modern IVC systems the CO(2) levels may reach 3-5% within a very short time, as the cages are very tightly sealed. The aim of the present study was to investigate the effects of 1%, 3%, and 5% CO(2) by studying the preferences of the animals as well as changes in the heart rate and systolic blood pressure as measured by telemetry. The rats avoided the cages, which contained 3% CO(2). In the telemetric study an anaesthetic effect on the rats were seen at 3% as a drop in the heart rate, and at 5% CO(2) a drop in the systolic blood pressure was also seen. The results from the present study could indicate that CO(2) levels of up to 3% do not affect the animals, or at least only to a minor extent, but that if the animals are exposed to CO(2) levels of higher than 3% they are affected directly as seen by changes in physiological parameters and preferences.

Animal Husbandry↗

PubMed2003

Higher heart rate of laboratory mice housed individually vs in pairs.

Many studies have shown that housing mice individually over a long period significantly alters their physiology, but in most cases measurement has required human interference and restraint for sampling. Using a radio-telemetry system with implantable transmitters, we recorded heart rate (HR), motor activity (ACT) and body temperature (BT) of freely moving male mice (NMRI) housed either individually or in pairs with an ovarectomized female. Data for each parameter were collected at 5 min intervals for two consecutive 24 h periods. Even after several weeks of habituation to the social conditions, HR was increased in mice housed individually compared with mice housed in pairs, although their measured ACT did not differ. Additionally, BT tended to be reduced in individually-housed mice. When the data were analysed according to different ACT levels, HR was increased in individually-housed mice during phases of low and high, but not intermediate, motor activity. Furthermore, individually-housed mice had more, but shorter, resting bouts, indicating disruption of the normal circadian sleep pattern. Enhanced HR in individually-housed mice does not necessarily indicate stress, but might be an important physiological indicator of discomfort. The fact that individual housing alters basic physiological parameters in laboratory mice highlights the need to control for housing-dependent variation, especially in experiments that are sensitive to changes in these parameters.

Animals↗

PubMed2006

The impact of different blood sampling methods on laboratory rats under different types of anaesthesia.

Rats with implanted telemetry transponders were blood sampled by jugular puncture, periorbital puncture or tail vein puncture, or sampled by jugular puncture in carbon dioxide (CO2), isoflurane or without anaesthesia in a crossover design. Heart rate, blood pressure and body temperature were registered for three days after sampling. Initially blood pressure increased, but shortly after sampling it decreased, which led to increased heart rate. Sampling induced rapid fluctuations in body temperature, and an increase in body temperature. Generally, rats recovered from sampling within 2-3 h, except for rats sampled from the tail vein, which showed fluctuations in body temperature in excess of 30 h after sampling. Increases in heart rate and blood pressure within the first hours after sampling indicated that periorbital puncture was the method that had the largest acute impact on the rats and that it might take an extra hour to recover from it. CO2 anaesthesia seemed unable to prevent the increase in blood pressure and the fluctuations in body temperature induced by blood sampling, and up to 10 h after sampling, the rats were still affected by CO2 anaesthesia. Rats anaesthetized with isoflurane showed lower increases in blood pressure after, and fewer fluctuations in body temperature during sampling, and the post-anaesthetic effects of isoflurane, if any, seemed to disappear immediately after sampling. It is, therefore, concluded that blood sampling in rats by jugular puncture seems to be the method from which rats most rapidly recover when compared with periorbital puncture and tail vein puncture, and that for anaesthesia, isoflurane is recommended in preference to CO2.

Anesthesia, Inhalation↗

PubMed1997

Continuous automated telecare assessment of the elderly.

An automated scheme is proposed to assess the ability of elderly people to live alone in the community. It employs an Enhanced Activities of Daily Living index based on a computerized questionnaire form. In addition, a number of low-cost sensors have been developed which provide electronic measures of certain activities; these can provide additional inputs to the assessment form using telemetry. The sensors are capable of measuring a wide range of functional performance, thus providing the means of continuously and objectively assessing a patient's condition following hospitalization.

Activities of Daily Living↗

PubMed2003

Enhanced depressor response to endothelial nitric oxide synthase gene transfer into the nucleus tractus solitarii of spontaneously hypertensive rats.

Previously, we demonstrated that endothelial nitric oxide synthase (eNOS) gene transfer into the nucleus tractus solitarii (NTS) decreased blood pressure, heart rate and sympathetic nerve activity in conscious normotensive Wistar-Kyoto rats (WKY). In order to determine whether overexpression of eNOS in the NTS causes different effects on blood pressure and heart rate between spontaneously hypertensive rats (SHR) and WKY, we transfected adenovirus vectors encoding either eNOS (AdeNOS) or beta-galactosidase (Ad beta gal) into the NTS of SHR and WKY in vivo. The local expression of eNOS in the NTS was confirmed by Western blot analysis for eNOS protein, and the magnitude of expression did not differ between SHR and WKY. Blood pressure and heart rate were monitored by the use of a radio-telemetry system in a conscious state before and 7 days after the gene transfer. Systolic blood pressure (SBP) and heart rate decreased on day 7 in both AdeNOS-transfected SHR and WKY. However, the magnitude of decreases in SBP of AdeNOS-transfected SHR was greater than that of AdeNOS-transfected WKY (-24.1 +/- 2.9 vs. -15.9 +/- 2.1 mmHg, p < 0.05). Transfection of Ad beta gal into the NTS did not alter SBP in either group. A depressor response evoked by microinjection of L-glutamate into the NTS did not differ between the two strains. These results suggest that overexpression of eNOS in the NTS causes a greater depressor response in SHR than in WKY in a conscious state. An abnormality of the L-arginine-NO pathway in the NTS may be related to the hypertensive mechanism(s) of SHR.

Animals↗

PubMed2006

The effect of intermittent administration of sustained release isosorbide dinitrate (sr-ISDN) in rats with volume overload heart.

Recently, it has been reported that intermittent administration of nitrate, with a nitrate-free interval of 10 to 12 hr eliminated expression of tolerance, and maintained its hypotensive effect. In the present study, we evaluated whether nitrate tolerance developed or not with an intermittent administration of sr-ISDN (5 mg/kg/ once a day) in Wistar rats. The effect of this administration protocol for sr-ISDN on the volume overload heart model, aortovenous fistula, was also examined. Furthermore, blood pressure was monitored by radio telemetry during sr-ISDN (5 mg/kg/once a day) administration. Nitrate tolerance did not develop, and eccentric hypertrophy due to volume overload was moderated by sr-ISDN administration. Sr-ISDN administration maintained blood pressure lower level than the placebo group. In conclusion, prolonged intermittent administration of sr-ISDN maintained its hypotensive effect during the entire experiment period, without developing tolerance, and moderated efferent hypertrophy with attenuated volume overload.

Analysis of Variance↗

PubMed2000

Changes in the loads on an internal spinal fixator after iliac-crest autograft.

Spines are often stabilised posteriorly by internal fixation and anteriorly by a bone graft. The effect of an autologous bone graft from the iliac crest on implant loads is unknown. We used an internal spinal fixation device with telemetry to measure implant loads for several body positions and activities in nine patients before and after anterior interbody fusion. With the body upright, implant loads were often higher after than before fusion using a bone graft. Distraction of the bridged region led to high implant loads in patients with a fractured vertebra and to marked changes in load in those with degenerative instability. Leaving the lower of the bridged intervertebral discs intact led to only small changes in fixator load after anterior interbody fusion. A bone graft alone does not guarantee a reduction of implant loads.

Adult↗

PubMed1976

Electrocardiographic radiotelemetry in the early recuperative period of acute myocardial infarction. Its value in detecting arrhythmias in the setting of a progressive coronary care unit.

One hundred seventeen consecutive patients with acute myocardial infarction transferred from the coronary care unit to a progressive coronary care unit were monitored by electrocardiographic radiotelemetry for a median of five days for arrhythmia detection. Eighty patients (68%) had arrhythmias; 37 patients (32%) had none. Almost all arrhythmias were detected by the sixth day of monitoring. Thirty-nine patients (33%) had premature ventricular contractions, two patients had primary ventricular tachycardia, one patient had primary ventricular fibrillation, and two patients had secondary ventricular fibrillation. An additional patient was successfully resuscitated after monitoring had been discontinued. Four (3%) of 117 patients had a potentially lethal arrhythmia treated successfully, three while being monitored. Twenty-five of the patients (21%) had 33 episodes of treatment intervention because of telemetrically detected events. Five patients (4%) died, all of unpreventable causes. No patient died because of an arrythmia. We conclude that telemetry is feasible and practical in detecting arrhythmias. It is clear that potentially fatal ventricular arrhythmias do occur following transfer from the coronary care unit and that monitoring is, therefore, desirable.

Acute Disease↗

PubMed2006

Animal models for cardiac arrhythmias.

Transgenic and gene-targeted mice are now frequently used to expand the study of cardiac physiology and pathophysiology owing to the ease with which the mouse genome can be manipulated. There are many measures by which an assessment of the phenotypical expression of the transgenic mouse can be made. In the case of cardiac channelopathies and how they relate to cardiac function, telemetry is a technology that utilizes transmitters that are surgically implanted in animals for the purpose of acquiring biopotentials or physiological parameters. Electrophysiological techniques have also been used to assess cardiac function at the cellular level, by measuring whole-cell ionic currents and/or transmembrane potentials. This chapter will discuss the surgical procedures involved in successfully implanting the transmitter device in a mouse, as well as highlight the recording of and analysis of electrocardiograms. This chapter will also outline the procedures involved in isolating single-ventricular myocytes from a mouse heart. It is a protocol that was developed in our laboratory for which we have routinely and successfully isolated myocytes from both transgenic and nontransgenic mouse hearts. Although no one isolation protocol is alike, we also present our own observations that have assisted in maximizing myocyte bioavailability and yield.

Animals↗

PubMed1991

[Continuous registration of the filling volume of the human urinary bladder].

A sensing system for continuous recording of bladder volume is described. The system is intended for use in particular in patients with paraplegia or bladder plastique. Owing to the very simple measuring procedure employed the implantable components can be designed for very low power consumption. Also, there is no need for an additional data transfer from inside the body to the exterior, because measurement and telemetry are physically the same procedures.

Equipment Design↗

PubMed2000

A simple, PC-dedicated, implanted digital PIM radiotelemetric system.

The short-distance, PC-dedicated implanted telemetry system is described. Schematic drawings of the transmitter and Centronics port interface are given and the main problems of the controlling program are discussed. The interface can be easily converted to serve as an analog output and the method of adaptation is demonstrated. The whole system was tested in animal experiments with two different amplifiers and the examples of resulting direct ECG and both direct and integrated intestinal EMG recordings are included.

Analog-Digital Conversion↗

PubMed2001

A simple, PC-dedicated, implanted digital PIM-radiotelemetric system. Part 2: The multichannel system.

The paper, which is a continuation of the previous one, describes a six-channel, PC-dedicated implanted telemetry system, including the schematic drawings, and explanation of all the differences between a single channel and multichannel system approach. The scheme of an additional multichannel analog output, that makes a pure analog recording possible, even without the PC connection, is also presented. Specific methods for both parallel (Centronics) and serial (RS232C) port interfacing are demonstrated and the controlling software principles are discussed. The representative recordings obtained from animal experiments of simultaneous (direct and integrated) multichannel intestinal EMG (MMC) are shown. The device can also be used for the ECG, EEG and uterine smooth muscle electrical activity recording.

Animals↗

PubMed2002

A telemetric measurement system for flow diagnostic after bypass surgery.

In medical applications minimal invasive techniques become more and more important. This paper is focused on the results of vascular flow measurements based on micromachined acceleration sensors. A telemetry circuit will be designed to transmit energy to the system and transmit data from it. The sensors were placed outside on artificial blood vessels. With special prepared measuring equipment we have varied the flow through elastic flexible tubes. The tubes were narrowed to different levels to simulate different states of a stenosis. The duty cycled output signals of the acceleration sensors modulates the amplitude of an analogue carrier frequency. The demodulator in the receiving module rebuilds the transferred sensor signals which are evaluated by a microcontroller.

Blood Flow Velocity↗