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PubMedDate not supplied

[Radiotelemetric study of heart rate and electroencephalogram during parachute jumping (author's transl)].

Twelve subjects, experienced parachutists, have been recorded by telemetry before, during and after free-fall parachute jumps. The heart rate showed a statistically significant tachycardia during the different events of the jump (exit, free-fall, opening, open parachute and landing) compared to the baseline before boarding the aircraft. This tachycardia indicates a stress reaction confirmed by a significant increase of adrenalin and noradrenalin in urine. The electroencephalographic invesitgation does not show any adnormalities. Alpha rhythms have been recorded from alpha reactive subjects during free-fall stabilization.

Aviation↗

PubMed1997

Positive epileptiform discharges in children with neuronal migration disorders.

Most epileptiform abnormalities show a negative polarity on EEG. Focal positive spike waves have rarely been identified in seizure disorders and are generally associated with physiological and neurological impairment. Results of EEG, computed tomography, MRI, and pathologic studies of 15 children with focal neuronal migration disorders who underwent surgery for refractory localization-related epilepsy were compared to examine the association between positive discharges and other findings. Subjects were studied both ictally and interictally by scalp EEG with the International 10-20 system and zygomatic or sphenoidal electrodes, and video EEG telemetry. The 5 children with positive discharges were significantly more likely to develop hemiparesis during the preoperative period (P < or = .025). Correlations were observed between positive discharges and lesions apparent on MRI situated around the rolandic fissure (P < or = .025). Children with positive discharges had a significantly less favorable outcome after surgical treatment (P < or = .025). Positive epilepti-form discharges in children with neuronal migration disorders may signal a more dysfunctional cortex leading to a focal neurological deficit or a more extended lesion than is detected on MRI. This would explain the less favorable outcome of seizures after surgery, since the epileptogenic areas and neuronal migration lesions cannot be completely resected.

Brain↗

PubMed1997

Bilateral tonic-clonic epileptic seizures in non-benign familial neonatal convulsions.

We report an electroclinical pattern considered characteristic of benign familial neonatal convulsions (BFNC) in two neonates without BFNC. Both neonates were products of uncomplicated pregnancies, labor, and deliveries. The cause of the seizures was not established. There was no family history of seizures or epilepsy. Seizures started on the second and third days after birth. Ten seizures were captured by continuous video-EEG telemetry. The electroclinical events began with generalized tonic posturing coinciding with the appearance of diffuse attenuation of the EEG activity. After several seconds, bilateral clonic movements accompanied by bilateral repetitive sharp waves or spikes occurred in the EEG. One patient had normal development; the other became autistic. We conclude that the electroclinical pattern occurring in BFNC can occur in other types of neonatal seizures.

Autistic Disorder↗

PubMed2001

Interaction between sodium intake, angiotensin II, and blood pressure as a cause of cardiac hypertrophy.

Cardiac hypertrophy is common in hypertension but its development is influenced by angiotensin II, sodium intake aldosterone, and the time of day blood pressure (BP) is elevated. This study examined and compared cardiac hypertrophy in the 2 kidney-1 clip (2K-1C) and 1 kidney-clip (1K-1C) Goldblatt models of hypertension. Blood pressure was measured by telemetry in a selected group of rats. Rats were placed on a high (4%) or reduced (0.2%) salt intake and were given captopril (75 mg/kg per day) or losartan (10 mg/kg per day). Appropriate sham-operated and untreated controls were used. Cardiac hypertrophy was greater in the IK-1C than in the 2K-1C model. Day and sleep BP were also higher. In the 2K-1C model BP was lower on the reduced salt intake and BP decreased with captopril in both reduced and high salt groups. Cardiac weight and index decreased significantly only in the reduced salt and captopril group and was less than the size before treatment. In the 1K-1C model captopril caused all BP measures to decrease in the reduced salt group but had no significant effect in the high salt group. Cardiac weight and index were reduced only in the reduced salt + captopril group and cardiac weight was less than the pretreatment control. Losartan had a similar effect in the lK-1C model to that achieved with captopril. The responses achieved correlated in part with renin status and dependency level. There is no prime determinant of cardiac hypertrophy. Blood pressure, sodium intake, and hormonal status are all important. It is postulated that the common pathway may be alterations in cell composition that signal the nucleus to increase cell growth.

Angiotensin II↗

PubMed1999

Serial changes in cardiovascular and renal function of rabbits ingesting a high-fat, high-calorie diet.

To explore the mechanisms of obesity-induced hypertension we analyzed the sequential changes in cardiovascular and renal function in adult rabbits switched to high-fat diet (HFD) for 8 weeks. Animals were housed in metabolic cages for continuous 24-h recording of arterial pressure by telemetry and daily urine collection. High-fat diet induced a progressive increase in body weight (+47%) and a rapid rise in mean arterial pressure, heart rate, and glomerular filtration rate that stabilized, respectively, at 14%, 31% and 68% greater than control values. Time-course analysis of changes in blood pressure may reveal two components of obesity-induced hypertension, an early phase related to HFD itself and a later phase related to weight gain.

Animals↗

PubMed1999

Aging but not sodium loading significantly attenuated diurnal change in blood pressure in stroke-prone spontaneously hypertensive rats.

In the present study, we evaluated the effect of aging on diurnal change in blood pressure in stroke-prone spontaneously hypertensive rats (SHRSP/Izm) using a telemetry system. Diurnal changes in blood pressure, heart rate, and locomotor activity were determined in unrestrained, freely moving condition in 24-week-old male SHRSP/Izm (n = 6) and 40-week-old male SHRSP/Izm (n = 6). Diurnal change in blood pressure was also investigated in 40-week-old male spontaneously hypertensive rats (SHR/Izm, n = 6) and Wistar-Kyoto rats (WKY/Izm, n = 5) as age-matched controls of the strain. All rats were kept in a 12-h light/dark cycle (light period from 06:00 to 18:00, and dark period from 18:00 to 06:00). Rats were active in dark phase and inactive in light phase. Mean blood pressures (MBP) were significantly higher in light phase as well as dark phase in old SHRSP/Izm compared with the other three groups. Light/dark phase ratio of MBP was significantly higher in old SHRSP/Izm compared with the other three groups. We observed a significant positive relationship between light/dark phase ratio of MBP and left ventricular mass index in a studied population of rats (r = 0.547, P < .01). Because SHRSP is a salt-sensitive model, the effect of high salt loading on the circadian pattern of blood pressure was also investigated. Male SHRSP/Izm, at the age of 22 weeks, were maintained on high salt (8%) for 2 weeks. High salt exposure significantly increased dark phase as well as light phase MBP in SHRSP/Izm. However, light/dark phase ratio of MBP was not significantly different from normal salt-fed (0.6%) SHRSP/Izm. These results indicate that aging and end-organ damage were associated with the alteration of diurnal change in blood pressure in SHRSP/Izm.

Aging↗

PubMed2000

Role of the sympathetic nervous system during the development of obesity-induced hypertension in rabbits.

We have previously reported that weight gain induced by high-fat diet (HFD) leads to an increase in mean arterial pressure (MAP, +14%) and heart rate (HR, +31%) in the adult rabbit. In the present study, we tested the hypothesis that an increased activity of the sympathetic nervous system may contribute to the development of obesity-induced hypertension. A combination of alpha- and beta-adrenergic blockers (terazosin + propranolol) was chronically administered to rabbits housed in metabolic cages for continuous monitoring of arterial pressure by telemetry, 24 h a day. After 2 weeks of adrenergic blockade under control diet, animals were switched to HFD for the next 6 weeks. HFD induced a progressive increase in body weight, but no increase in mean arterial pressure (+0.2+/-2.5%) and a slight increase in heart rate (+14+/-3%). Time-control animals fed normal diet showed no changes in MAP or HR with long-term alpha- and beta-adrenergic blockade. Our results indicate that the activation of the sympathetic nervous system may play an important role in the pathogenesis of obesity-induced hypertension.

Adrenergic alpha-Antagonists↗

PubMed1998

Abnormal heart rate regulation in GIRK4 knockout mice.

Acetylcholine (ACh) released from the stimulated vagus nerve decreases heart rate via modulation of several types of ion channels expressed in cardiac pacemaker cells. Although the muscarinic-gated potassium channel I(KACh) has been implicated in vagally mediated heart rate regulation, questions concerning the extent of its contribution have remained unanswered. To assess the role of I(KACh) in heart rate regulation in vivo, we generated a mouse line deficient in I(KACh) by targeted disruption of the gene coding for GIRK4, one of the channel subunits. We analyzed heart rate and heart rate variability at rest and after pharmacological manipulation in unrestrained conscious mice using electrocardiogram (ECG) telemetry. We found that I(KACh) mediated approximately half of the negative chronotropic effects of vagal stimulation and adenosine on heart rate. In addition, this study indicates that I(KACh) is necessary for the fast fluctuations in heart rate responsible for beat-to-beat control of heart activity, both at rest and after vagal stimulation. Interestingly, noncholinergic systems also appear to modulate heart activity through I(KACh). Thus, I(KACh) is critical for effective heart rate regulation in mice.

Adenosine↗

PubMed2001

Ultradian and circadian body temperature and activity rhythms in chronic MPTP treated monkeys.

The body temperature and locomotor activity rhythms of seven 1-Methyl, 4-phenyl, 1,2,3,6-tetrahydropyridine (MPTP)-treated cynomolgous monkeys were registered over a week on two separate occasions over an interval of 2 months. Motor disability was absent in two animals and present in five: it was mild in one, moderate in two and severe in two. Both temperature and motor activity were recorded every minute using a radio telemetry system. Analysis of circadian rhythms revealed less robustness of the 24-hour circadian components of body temperature and locomotor activity with increasing motor impairment, and a fragmentation of the body temperature rhythm into 8 hour-period components. Both total activity and daytime activity correlated inversely with the degree of motor impairment. On the contrary, the monkeys did not show differences in night time activity. The proportions of variance accounted for by the body temperature and locomotor activity of 24 h + 12 h + 8 h components were correlated. Also, the average levels at which the circadian rhythm varies between body temperature and locomotor activity were correlated. The results were almost identical in the two 1-week recording sessions. The present study confirms individual differences in the vulnerability to MPTP of the nigrostriatal system of monkeys, suggesting that if a cumulative dose does not provoke stable motor alterations, this cumulative dose will not produce circadian body temperature and locomotor activity rhythm alterations either. Similarly, if a dose is able to produce motor impairment, this dose will also be able to produce circadian rhythm alterations.

Activity Cycles↗

PubMed2003

A radiotelemetry system for polysomnographic recordings in lambs.

The use of telemetry in biomedical research is rapidly increasing and is soon likely to be standard in research fields where prolonged recordings of multiple physiologic variables are necessary in freely moving animals. We describe our experience with a radiotelemetry system designed in our laboratory for polysomnographic recordings in newborn lambs. The system comprises eight channels: four channels for electromyographic activity of respiratory muscles, and one channel each for electrocorticogram, eye movement, electrocardiogram, and nasal flow. Using this system, we report our experience on the study of respiration and spontaneous apneas in the various states of consciousness, based on more than 500 h of recordings. Addition of radiotelemetry to our armamentarium has proven to be of invaluable help for the study of neonatal apneas and has now become routine in our laboratory.

Animals↗

PubMed2003

Brain temperature measurement and regulation in awake and freely moving rodents.

Temperature measurement and control are essential in most ischemia experiments. Hypothermia lessens ischemic brain injury whereas hyperthermia exacerbates it. A substantial number of ischemia studies rely solely on rectal temperature measurements during the insult. However, rectal temperature may not accurately reflect brain temperature especially during global ischemia. Furthermore, postischemic temperature changes are often inadequately monitored. Delayed cooling reduces injury, whereas delayed hyperthermia aggravates it. This review summarizes our experiences with core and brain telemetry probes to continually measure temperature in various ischemia models. Furthermore, we discuss methods to simultaneously measure and regulate temperature in the freely moving postischemic rodent, and the need for such control in ischemia research.

Animals↗

PubMed2001

The influence of geographic variations on the muscular activity in selected sports movements.

Surface EMG (SEMG) has been used frequently to study motion techniques or skills, body positions, material or equipment used, training-methodology and learning processes in sports and ergonomics. Little if any information is available on the effect of the geographical environment on the neuromuscular control of an athlete or workman during his/her performance or effort. Motions were chosen in Alpine skiing and cycling. Thirty-one certified ski instructors and twelve professional road cyclists participated in the study of geographical variance and its impact on muscle activity. SEMG was measured from the agonists and antagonists of the upper- and lower limb. Skiers were measured on downhill slopes ranging from 19 to 51% while the cyclists performed with different saddle positions on 2, 7 and 12% slope inclinations, respectively. Verification of the variation of muscular intensity (IEMG) over the slope inclination during a simulated giant slalom indicated that the muscular activity increased with increasing slope angle and decreased with decreasing slope angle, while heart rate measured with short-range radio telemetry increased at a constant rate between start and finish independent of the geographical variations. In a direct descent on different slopes % levels the integrated EMG is well related to the inclination (r=0.82) confirming the findings of the giant slalom. In cycling we found that, regardless of the pelvis position, the muscular intensity of lower limb muscles increased with increasing slope inclination, while the muscular intensity of the arms decreased with the same increasing slope inclination. In addition the decreased intensity of the arm muscles remained significantly higher with the pelvis (saddle) fully forward. The geography of the terrain did influence the neuromuscular work and therewith probably the performance also. The influence however, varies with specific circumstances and is coupled with items of variability of the equipment used and the body regions involved.

Adult↗

PubMed2000

Monitoring pig-to-primate cardiac xenografts with live Internet images of recipients and xenograft telemetric signals: histologic and immunohistochemical correlations.

BACKGROUND: Monitoring pig-to-primate cardiac xenografts is often difficult in awake and uncooperative primates. We investigated the possibility of monitoring xenotransplantation through Internet broadcasting of (1) continuous video images of transplant recipients and (2) xenograft telemetric signals detected by an implanted device. The telemetric readings were later compared with histology and immunohistochemistry for signs of rejection. METHODS: Heterotopic baboon-to-baboon (n = 2) and transgenic pig (human complement regulatory proteins CD59/DAF, n = 3; MCP, n = 1)-to-baboon transplants were performed with serial biopsies for hematoxylin-and-eosin staining and immunohistochemical detection of immunoglobulin M (IgM) and complement membrane attack complex (MAC) deposition. Baboon recipients were continuously monitored with a QuickCamPro digital camera, whereas grafts were monitored with a Data Science International implantable telemetric system. Video images and telemetric signals were broadcast over the Internet through a laptop computer. RESULTS: Baboon allografts remained healthy until explant on Day 14, whereas pig xenografts were rejected on Day 5, 6, 7, and 11. Telemetry of allografts and xenografts documented regular rhythm with an average heart rate of 80 to 120, but xenografts developed bradycardia and widened/dampened QRS complexes 24 to 48 hours before graft loss. Continuous video monitoring of recipient activities was vital in differentiating between graft arrhythmias and telemetric artifacts. Allograft biopsies showed little cellular infiltrate, whereas xenograft biopsies showed increasing IgM and MAC deposition, with extensive thrombi and myocardial damage 24 hours before cessation of cardiac activities. CONCLUSIONS: Combined video surveillance of recipient activities and graft telemetric signals is a useful method to continuously monitor abdominal cardiac grafts in large, uncooperative, awake primates. QRS-complex widening associated with progressive bradycardia correlated with histologic and immunohistochemical evidence of xenograft rejection.

Animals↗

PubMedDate not supplied

A novel method for chronic measurement of respiratory function in the conscious monkey.

INTRODUCTION: Chronic measurement of respiratory function in the conscious monkey has been limited by the ability to monitor pleural pressure. Previous attempts to measure pleural pressure chronically in conscious animals have involved surgical implantation of pressure-sensitive catheters directly into the pleural cavity. The success of these techniques has been limited by lung damage and/or tissue growth and encapsulation of the pressure-sensitive catheter with damping or loss of the signal. These problems have been eliminated by developing a novel surgical procedure for placement of a pressure-sensitive catheter beneath the pleural surface. METHODS: A pressure-sensitive catheter (attached to a radiotelemetry transmitter) was surgically implanted beneath the serosal layer of the esophagus within the thoracic cavity. This was accomplished by performing a midline laparotomy, making a small incision in the serosal layer of the esophagus caudal to the diaphragm, and advancing the catheter cranially along the esophagus and beneath the serosal layer into the thoracic cavity. The catheter was secured to the esophageal wall and the telemetry transmitter was sutured to the inner abdominal wall. Respiratory airflow measurements were obtained using a restraint chair equipped with a clear plastic helmet (plethysmograph chamber) that seals around the neck and encloses the head. RESULTS: The decreases in pleural pressure during inspiration ranged from -5 to -15 mmHg and remained constant for at least 36 weeks following surgery. Intravenous administration of the respiratory depressant morphine, exposure to the respiratory stimulant 8% CO2, and intravenous administration of the bronchoconstrictive agent methacholine verified that this technique was able to detect and quantify ventilatory changes and an increase in airway resistance. DISCUSSION: This novel method for chronic measurement of pleural pressure will facilitate evaluation of the effects of drugs, environmental agents, or disease on respiratory function by allowing repeated measurements of both ventilatory (breathing) patterns and the mechanical properties of the lung in a conscious nonhuman primate.

Airway Resistance↗

PubMedDate not supplied

Rat tail skin temperature monitored noninvasively by radiotelemetry: characterization by examination of vasomotor responses to thermomodulatory agents.

INTRODUCTION: Measurement of tail skin temperature (T(sk)) of the rat can provide important information on mechanisms pertaining to physiology, pharmacology, and toxicology. T(sk) is largely under control of peripheral vascular tone, which is also sensitive to most experimental manipulations such as handling and restraint. Hence, it is extremely difficult to acquire long-term measurements of T(sk) that are free of artifacts from experimental manipulation. The purpose of this study is to demonstrate the utility of a radiotelemetric probe to provide continuous, long-term measurements of T(sk) in undisturbed rats. METHODS: A telemetry probe is placed on the base of the tail and secured with a protective guard to prevent the rat from chewing on the probe. T(sk) is continuously monitored with standard radiotelemetric software and computer technology. Core temperature (T(c)) is monitored in duplicate sets of rats at the same time but the current system does not allow for simultaneous measurement of T(sk) and T(c) from the same animal. Rats were subjected to a variety of experimental manipulations to demonstrate the utility of the probe. RESULTS/DISCUSSION: A marked increase in T(sk) was seen during the transition from light to dark phase, reflecting an increase in heat loss to lower T(c); a decrease in T(sk) during the development of endotoxin-induced fever, reflecting a reduction in heat loss to facilitate an elevation in T(c); an increase in T(sk) following exposure to the organophosphate insecticide chlorpyrifos, reflecting an increase in heat loss to facilitate a hypothermia response; and a direct effect of increasing ambient temperature on T(sk). The probe is relatively inexpensive and is used with no surgery and provides long-term measurement (e.g., >24 h) of T(sk) in unrestrained rats.

Animals↗

PubMed1998

A pharmacological validation of radiotelemetry in conscious, freely moving rats.

Two reference substances were used in the present study. d-Amphetamine is a direct catecholamine-releasing agent which has a marked stimulant effect upon locomotor activity at low to moderate doses and induces stereotypy at higher doses. (+/-)8-Hydroxy-2-(di-n-propylamino)-tetraline [(+/-)8-OH-DPAT] is a selective 5-HT1A receptor agonist which produces a well-defined behavioral syndrome and a dose-dependent hypothermia. The first aim of this study was to validate that the d-amphetamine-induced activity monitored by telemetry correlated to that concomitantly measured in automated cages and complement these measures with an ethologically based direct observational technique. d-Amphetamine (2.5 and 5.0 micromol/kg s.c.) stimulated locomotion as assessed with radiotelemetry, in automatic cages and by observation. Accompanying these behavioral effects was a concurrent increase (assessed by radiotelemetry) in heart rate but not in blood pressure. The second part of this study examined the pharmacological effects of (+/-)8-OH-DPAT (0.09-6.1 micromol/kg s.c.) on behavior (observation and activity) and temperature and on the cardiovascular system. (+/-)8-OH-DPAT induced the classical serotonergic syndrome of lower lip retraction, forepaw treading, and flattened body posture (observation), and this was accompanied by a concomitant hypothermia (radiotelemetry). (+/-)8-OH-DPAT also induced a dose-dependent and significant decrease in heart rate for 50 min of the 1-h long observation period. This was not accompanied by an increase in blood pressure in spite of the increased activity as seen with all three methods. These results show that radiotelemetry can be used as a tool to measure activity, core temperature, and the cardiovascular parameters in animals that are less stressed than those that are restrained for similar more invasive measurements, and that this technique can be used in combination with others to produce a more complete ethogram of the animal's responses to pharmacological challenges.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed2004

Comparison of objective and subjective measurements of cough frequency in patients with seasonal allergic rhinitis.

BACKGROUND: Cough is a frequent complaint of patients with a variety of respiratory disorders, including seasonal allergic rhinitis (SAR), and it is often evaluated subjectively to determine disease status and response to treatment. However, it is not known whether subjective reports of cough from patients with SAR are accurate. OBJECTIVE: To compare a novel objective measurement with subjective reports of cough frequency in a subset of 28 patients (aged > or = 12 years) with active SAR who were enrolled in a large, multicenter trial examining the efficacy of an active treatment for SAR. METHODS: In this supplemental pilot study, subjective data were collected on a diary card and objective data were collected using home-based telemetry. Three 24-hour recording sessions were conducted with each patient: 2 consecutive baseline sessions (day 1 and day 2) and 1 session after randomization to placebo or active cough treatment (day 3). RESULTS: Strong correlations existed between cough frequency data for days 1 and 2 (Spearman correlation coefficient = 0.91; P < .001) and between subjective and objective data for days 1, 2, and 3 (daytime greater than nighttime) (Spearman correlation coefficient = 0.51; P < .001). CONCLUSION: These results have implications for the design and interpretation of results from clinical trials that evaluate cough frequency as a treatment outcome.

Adolescent↗

PubMed2000

Concept, design and fabrication of smart orthopedic implants.

Extensive clinical experience has been built up using orthopaedic implants instrumented with strain gauges connected to a Wheatstone bridge by means of percutaneous leads. This research showed the medical relevance of the monitoring of the deformation of implants as a powerful tool to evaluate nursing and rehabilitation exercises, for tracing dangerous overloads and anticipating implant failure and also to observe the healing process. The IMPACT 3500 project focuses on the instrumentation of femoral implants with on board sensors: regular Benoist-Girard implants have been modified, to contain a 'sensing cell', and thoroughly tested in vitro and in vivo. The implant deformations are measured with resistive strain gauges, and the signal is transferred to a personal computer for processing and display, via a hard wired connection, or via a telemetry system. Two fully implantable wireless designs, called Linkstrain and Sealstrain, are powered from the outside by magnetic induction. As Sealstrain contains the whole telemetric system in its cavity, the highest miniaturization was required; this seriously deteriorates the efficiency of the inductive power link.

Biocompatible Materials↗