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At least 1,369 records · Page 76Linked to original sources

PubMed2003

Metabolic heat production, heat loss and the circadian rhythm of body temperature in the rat.

Metabolic heat production (calculated from oxygen consumption), dry heat loss (measured in a calorimeter) and body temperature (measured by telemetry) were recorded simultaneously at 6 min intervals over five consecutive days in rats maintained in constant darkness. Robust circadian rhythmicity (confirmed by chi square periodogram analysis) was observed in all three variables. The rhythm of heat production was phase-advanced by about half an hour in relation to the body temperature rhythm, whereas the rhythm of heat loss was phase-delayed by about half an hour. The balance of heat production and heat loss exhibited a daily oscillation 180 deg out of phase with the oscillation in body temperature. Computations indicated that the amount of heat associated with the generation of the body temperature rhythm (1.6 kJ) corresponds to less than 1 % of the total daily energy budget (172 kJ) in this species. Because of the small magnitude of the fraction of heat balance associated with the body temperature rhythm, it is likely that the daily oscillation in heat balance has a very slow effect on body temperature, thus accounting for the 180 deg phase difference between the rhythms of heat balance and body temperature.

Animals↗

PubMed2005

Relationship between dietary-induced changes in intestinal commensal microflora and duodenojejunal myoelectric activity monitored by radiotelemetry in the rat in vivo.

Interdigestive intestinal motility, and especially phase III of the migrating myoelectric/motor complex (MMC), is responsible for intestinal clearance and plays an important role in prevention of bacterial overgrowth and translocation in the gut. Yet previous results from gnotobiotic rats have shown that intestinal microflora can themselves affect the characteristics of the myoelectric activity of the gut during the interdigestive state. Given that the composition of the intestinal microflora can be altered by dietary manipulations, we investigated the effect of supplementation of the diet with synbiotics on intestinal microflora structure and the duodenojejunal myoelectric activity in the rat. To reduce animal distress caused by restraint and handling, which can itself affect GI motility, we applied radiotelemetry for duodenojejunal EMG recordings in conscious, freely moving rats. Thirty 16-month-old Spraque-Dawley rats were used. The diet for 15 rats (E group) was supplemented with chicory inulin, Lactobacillus rhamnosus and Bifidobacterium lactis. The remaining 15 rats were fed control diet without supplements (C group). Three rats from each group were implanted with three bipolar electrodes positioned at 2, 14 and 28 cm distal to the pylorus. After recovery, two 6 h recordings of duodenojejunal EMG were carried out on each operated rat. Subsequently, group C rats received feed supplements and group E rats received only control diet for 1 week, and an additional two 6 h recordings were carried out on each of these rats. Non-operated C and E rats were killed and samples of GI tract were collected for microbiological analyses. Supplementation of the diet with the pro- and prebiotics mixture increased the number of bifidobacteria, whereas it decreased the number of enterobacteria in jejunum, ileum, caecum and colon. In both caecum and colon, the dietary supplementation increased the number of total anaerobes and lactobacilli. Treatment with synbiotics increased occurrence of phase III of the MMC at all three levels of the small intestine. The propagation velocity of phase III in the whole recording segment was also increased from 3.7 +/- 0.2 to 4.4 +/- 0.2 cm min(-1) by dietary treatment. Treatment with synbiotics increased the frequency of response potentials of the propagated phase III of the MMC at both levels of the jejunum, but not in the duodenum. In both parts of the jejunum, the supplementation of the diet significantly decreased the duration of phase II of the MMC, while it did not change the duration of phase I and phase III. Using the telemetry technique it was demonstrated that changes in the gastrointestinal microflora exhibited an intestinal motility response and, more importantly, that such changes can be initiated by the addition of synbiotics to the diet.

Animals↗

PubMed2006

Roux-en-Y or 'uncut' Roux procedure? Relation of intestinal migrating motor complex recovery to the preservation of the network of interstitial cells of Cajal in pigs.

We designed a conscious pig model to investigate myoelectric activity and the number of interstitial cells of Cajal (ICC) in the proximal jejunum following the Roux-en-Y and 'uncut' Roux procedures in relation to clinical outcomes. Twelve male Polish White pigs (8 weeks old, 10-13 kg) underwent surgery under general anaesthesia first to implant bipolar electrodes and telemetry transmitters for continuous electromyography recordings and then, after 1 week recovery, to create Roux-en-Y (n = 6) and 'uncut' Roux loops (n = 6). Upper gut tissue specimens were studied for the expression of c-kit staining procedure to quantitatively identify the presence of interstitial cells of Cajal. The intestinal migrating motor complex was restored within 10.5 and 37 h in 'uncut' Roux and Roux-en-Y pigs, respectively (P < 0.05). During 2 weeks, the 'uncut' Roux piglets increased their body weight by 18.0%, whereas the Roux-en-Y piglets increased their body weight by only 7.3% (P < or = 0.05). Two weeks after surgery, the number of ICC located in the region of Auerbach's plexus was higher and adhesions in the abdominal cavity lower in the 'uncut' Roux group. In conclusion, in the pig model, preservation of smooth muscle and ICC network continuity in the proximal jejunum may play an important role in early postsurgical recovery.

Animals↗

PubMed1968

Parturient pressures in the ovine uterus.

1. Intra-uterine pressure changes were followed by radio-telemetry in ten ewes carrying one lamb in each horn. One endo-radiosonde was implanted in each horn some 2-3 weeks before term and the pressure changes in the two horns were recorded simultaneously thereafter.2. The first isolated pressure waves which could be ascribed to myometrial activity were detected about 12 hr before delivery. Once pressure waves had become established, it was found that one horn developed waves which were about double the amplitude of those in the other horn and of greater duration. Thus one horn became dominant and the lamb occupying this horn was the first to be presented at the cervix. There appeared to be no difference between the two horns in the frequency of the waves.3. Digital examination of the os led to a phase of increased pressure waves which was considered to be due to oxytocin release.4. These findings are discussed and it is suggested that some local factor maintains the dominance of one horn and that this factor may be related to the local influence of the placenta.

Animals↗

PubMed1977

Reflexes in cat ankle muscles after landing from falls.

1. Electrical activity and length of ankle muscles were recorded by telemetry during free fall and landing in cats. 2. After foot contact, there was a delay in onset of stretch of ankle extensors of between 8 and 11 ms. High-speed cinematography showed the delay to be associated with rapid initial dorsiflexion of the toes. 3. Electromyograms (e.m.g.) from lateral gastrocnemius increased in amplitude prior to landing. An early depression of lateral gastrocnemius e.m.g. commenced at 8 ms after foot contact, and was followed by a large peak of activity commencing some 8 ms after the first increase in lateral gastrocnemius length. 4. Local anaesthesia of the plantar cushion did not alter this pattern of response. 5. The early inhibition of lateral gastrocnemius was attributed to the action on lateral gastrocnemius motoneurones of non-cutaneous afferents responding to the initial toe dorsiflexion. Additional autogenetic inhibition may also have contributed. 6. The subsequent peak of e.m.g. was at a latenty consistent with a rapid stretch reflex, and occurred soon enough for the resulting active tension to contribute significantly to the extensor force during body deceleration.

Animals↗

PubMed2004

Neuropeptide Y stabilizes body temperature and prevents hypotension in endotoxaemic rats.

The on-going high mortality from sepsis motivates continuous research for novel therapeutic strategies. Neuropeptide Y (NPY), a sympathetic neurotransmitter, has been shown to increase survival in experimental septic shock in rats. This protective effect might be due to immunological, cardiovascular or thermoregulatory effects. The aim of this study was to examine the in vivo effect of peripherally administered NPY on body temperature, blood pressure and heart rate in endotoxaemic animals. In order to obtain clinically relevant data, various physiological parameters were monitored in parallel via radio-telemetry in chronically intravenously cannulated, freely behaving rats. Rats received a sublethal bolus of lipopolysaccharide (LPS, 100 microg kg(-1) I.V.) and the three parameters were continuously recorded for 72 h. Endotoxaemic rats showed a long-lasting hypotension, an initial hypothermia (-0.5 degrees C), followed by a prolonged febrile phase (+1.6 degrees C 6 h after endotoxin challenge) associated with a decrease of the circadian rhythm amplitude of temperature. Pretreatment with NPY (160 pmol kg(-1) I.V. over 75 min) prevented hypotension and significantly stabilized body temperature immediately following the application. The febrile phase was effectively reduced for at least 72 h. These telemetrically obtained findings clearly demonstrate that pretreatment with NPY positively influences two life-threatening symptoms in endotoxaemia and might be a future option for a successful clinical treatment regimen.

Animals↗

PubMed1975

Chronotypic action of theophylline and of pentobarbital as circadian zeitgebers in the rat.

In the rat the deep body temperature rhythm, monitored by telemetry, can be reset in a predictable direction by a stimulant (theopylline) and by a depressant (pentobarbital). When the drugs are applied immediately before or during the early active phases of the circadian cycle, the rhythm is set back (phase delay). When applied later, past the thermal peak, theophylline, but not pentobarbital, shifts the rhythm ahead (phase advance). Theophylline and pentobarbital in addition to having a number of already established pharmacological properties are now further identified as chronobiotics: they are drugs that may be used to alter the biological time structure by rephasing a circadian rhythm.

Animals↗

PubMed1971

Telemetered recording of hormone effects on hippocampal neurons.

Frequency-modulated telemetry was used to record the effects of hormones on single-unit activity in the brains of freely moving rats. Corticosterone decreased unit activity in the dorsal hippocampus. Adrenocorticotrophic hormone had the opposite effect.

Adrenocorticotropic Hormone↗

PubMed1997

Energy expenditure and physiological responses during indoor rock climbing.

OBJECTIVES: To report the physiological responses of indoor rock climbing. METHODS: Fourteen experienced climbers (nine men, five women) performed three climbing trials on an indoor climbing wall. Subjects performed three trials of increasing difficulty: (a) an easy 90 degrees vertical wall, (b) a moderately difficult negatively angled wall (106 degrees), and (c) a difficult horizontal overhang (151 degrees). At least 15 minutes separated each trial. Expired air was collected in a Douglas bag after four minutes of climbing and heart rate (HR) was recorded continuously using a telemetry unit. Arterialised blood samples were obtained from a hyperaemised ear lobe at rest and one or two minutes after each trial for measurement of blood lactate. RESULTS: Significant differences were found between trials for HR, lactate, oxygen consumption (VO2), and energy expenditure, but not for respiratory exchange ratio. Analysis of the HR and VO2 responses indicated that rock climbing does not elicit the traditional linear HR-VO2 relationship characteristic of treadmill and cycle ergometry exercise. During the three trials, HR increased to 74-85% of predicted maximal values and energy expenditure was similar to that reported for running at a moderate pace (8-11 minutes per mile). CONCLUSIONS: These data indicate that indoor rock climbing is a good activity to increase cardiorespiratory fitness and muscular endurance. In addition, the traditional HR-VO2 relationship should not be used in the analysis of this sport, or for prescribing exercise intensity for climbing.

Adult↗

PubMed1997

Energy expenditure estimates of the Caltrac accelerometer for running, race walking, and stepping.

OBJECTIVE: To examine the accuracy of the Caltrac accelerometer for estimating energy expenditure (EE) during three exercise modes. METHODS: A subset of 31 women (mean (SEM) age 22.6 (5) years) as selected from a training study comparing various physiological parameters during race walking, running, and stepping. Subjects each performed mode specific graded exercise tests to peak VO2. Regression equations for VO2 v heart rate (HR) were generated from each individual's test data. EE (kcal and kJ) was estimated for each VO2 value based on the respiratory exchange ratio, and kcal v HR regression equations were generated to predict EE from each subject's HR data (EE-HR). HR in the field was monitored by telemetry, and two Caltrac monitors, one set for EE and one to give counts, were attached to a belt over opposite hips. RESULTS: EE-HR was not significantly different across exercise modes. Caltrac overestimated EE (P < 0.01) in runners (14%) and walkers (19%) but underestimated EE in steppers by about 10% (P = 0.12). CONCLUSIONS: The Caltrac is a reliable instrument but it did not accurately distinguish EE in running, race walking, or stepping in a group of young women.

Acceleration↗

PubMed1982

Telemetered EEG in schizophrenia: spectral analysis during abnormal behaviour episodes.

In an attempt to detect electroencephalographic (EEG) changes associated with characteristic clinical signs and symptoms of schizophrenia, power spectra were derived from scalp EEGs of schizophrenic patients recorded by telemetry during free behaviour on their psychiatric wards. Power spectra from EEG epochs coincident with psychomotor blocking, stereotyped automatism or hallucinations were compared with spectra derived during periods of relatively normal behaviour, during performance of specific tasks and spectra from control subjects. Ramp spectra, characterised by a smooth decline in power from lowest to highest frequencies, previously found in conjunction with subcortical spike activity of epilepsy were not found in any control subject, but appeared in spectra from schizophrenic patients during catatonic episodes, hallucinatory periods and visual checking. Schizophrenic patients also had more slow activity and less alpha activity in their EEGs than normal control subjects.

Adult↗

PubMed1994

Use of the hand held video camcorder in the evaluation of seizures.

Epilepsy is primarily a clinical diagnosis and eye witness accounts are invaluable in the differential diagnosis of seizures, but may be incomplete or misleading. A hand held video camcorder was used in this study to record seizures of patients to clarify the nature of their attacks. The videotapes assisted the diagnosis of non-epileptic attacks in nine of 22 patients (41%), and of epileptic attacks in eight of 22 patients (36%). Interactions with patients during filming were particularly helpful. Five patients (23%) could not be filmed, three of whom had seizures that were too shortlived to be recorded. In two patients (9%) a confident diagnosis of non-epileptic seizures could be made from the videotapes alone. Seven patients subsequently required video-EEG telemetry. It is concluded that the hand held video camera is a useful and inexpensive tool to provide accurate seizure descriptions, but it should be used in conjunction with other evidence to classify seizures.

Adolescent↗

PubMed1995

Characteristics of wheeze during histamine-induced airways obstruction in children with asthma.

BACKGROUND: An automated system has been developed for the detection of sound patterns suggestive of airways obstruction in long term recordings. The first step, presented here, was tracheal sound recording during histamine-induced airways obstruction. METHODS: The tracheal sounds of 29 children aged 8-19 years with asthma were recorded during airways obstruction caused by histamine inhalation using a system for continuous respiratory telemetry and computer analysis. Sound patterns were analysed, classified, and related to airways obstruction measured by lung function tests based on the forced expiratory volume in one second (FEV1). RESULTS: Five sound patterns were identified, one dominant sensitive and four specific to a fall in FEV1 of > 20%. The presence of at least one of three specific sound patterns during unforced respiration predicted a fall in FEV1 of > 20% in 87.5% of the subjects. The inspiratory and expiratory sound patterns were almost equally informative of airways obstruction. CONCLUSIONS: Wheezes can be differentiated with more precision than is currently accepted. Tracheal sound patterns are sensitive and specific predictors of histamine-induced airways obstruction. These patterns are neither invariably nor proportionally related to the results of lung function testing. However, they can be used for detection of airways obstruction on the basis of their presence or absence.

Adolescent↗

PubMed2002

The cardiorespiratory response and energy expenditure of Tai-Chi-Qui-Gong.

The purpose of this study was to evaluate the cardiorespiratory response and energy expenditure during the practice of Tai-Chi-Qui-Gong (TCQG). Forty-seven TCQG practitioners with a mean age of 60.7 +/- 9.9 years participated in this study. The cardiorespiratory responses and energy expenditure were measured by a K4 telemetry system. TCQG has 54 motions and can be divided into 3 sets. The result indicated that the exercise intensity of each motion is about 3 metabolic equivalents (MET) and the energy expenditure of each set is about 60 Kcal. The estimated intensity of TCQG in elderly individuals approximated 50% of the maximum oxygen uptake (vO2max) for men, and 60% of the maximum oxygen uptake (vO2max) for women. The findings demonstrate that TCQG is a low intensity exercise and can be prescribed as an alternative exercise program for cardiopulmonary rehabilitation.

Adult↗

PubMed1999

Injectable electronic identification, monitoring, and stimulation systems.

Historically, electronic devices such as pacemakers and neuromuscular stimulators have been surgically implanted into animals and humans. A new class of implants made possible by advances in monolithic electronic design and implant packaging is small enough to be implanted by percutaneous injection through large-gauge hypodermic needles and does not require surgical implantation. Among these, commercially available implants, known as radio frequency identification (RFID) tags, are used for livestock, pet, laboratory animal, and endangered-species identification. The RFID tag is a subminiature glass capsule containing a solenoidal coil and an integrated circuit. Acting as the implanted half of a transcutaneous magnetic link, the RFID tag is powered by and communicates with an extracorporeal magnetic reader. The tag transmits a unique identification code that serves the function of identifying the animal. Millions of RFID tags have been sold since the early 1980s. Based on the success of the RFID tags, research laboratories have developed injectable medical implants, known as micromodules. One type of micromodule, the microstimulator, is designed for use in functional-neuromuscular stimulation. Each microstimulator is uniquely addressable and could comprise one channel of a multichannel functional-neuromuscular stimulation system. Using bidirectional telemetry and commands, from a single extracorporeal transmitter, as many as 256 microstimulators could form the hardware basis for a complex functional-neuromuscular stimulation feedback-control system. Uses include stimulation of paralyzed muscle, therapeutic functional-neuromuscular stimulation, and neuromodulatory functions such as laryngeal stimulation and sleep apnea.

Animal Identification Systems↗

PubMed2002

Hypertension induced by blockade of ET(B) receptors in conscious nonhuman primates: role of ET(A) receptors.

The role of endothelin-B (ET(B)) receptors in circulatory homeostasis is ambiguous, reflecting vasodilator and constrictor effects ascribed to the receptor and diuretic and natriuretic responses that could oppose the hypertensive effects of ET excess. With the use of conscious, telemetry-instrumented cynomolgus monkeys, we characterized the hypertension produced by ET(B) blockade and the role of ET(A) receptors in mediating this response. Mean arterial pressure (MAP) and heart rate (HR) were measured 24 h/day for 24 days under control conditions and during administration of the ET(B)-selective antagonist A-192621 (0.1, 1.0, and 10 mg/kg bid, 4 days/dose) followed by coadministration of the ET(A) antagonist atrasentan (5 mg/kg bid) + A-192621 (10 mg/kg bid) for another 4 days. High-dose ET(B) blockade increased MAP from 79 +/- 3 (control) to 87 +/- 3 and 89 +/- 3 mmHg on the first and fourth day, respectively; HR was unchanged, and plasma ET-1 concentration increased from 2.1 +/- 0.3 pg/ml (control) to 7.24 +/- 0.99 and 11.03 +/- 2.37 pg/ml. Atrasentan + A-192621 (10 mg/kg) decreased MAP from hypertensive levels (89 +/- 3) to 75 +/- 2 and 71 +/- 4 mmHg on the first and fourth day, respectively; plasma ET-1 and HR increased to 26.64 +/- 3.72 and 28.65 +/- 2.89 pg/ml and 113 +/- 5 (control) to 132 +/- 5 and 133 +/- 7 beats/min. Thus systemic ET(B) blockade produces a sustained hypertension in conscious nonhuman primates, which is mediated by ET(A) receptors. These data suggest an importance clearance function for ET(B) receptors, one that influences arterial pressure homeostasis indirectly by reducing plasma ET-1 levels and minimizing ET(A) activation.

Animals↗

PubMed2002

Calcium-dependent arrhythmias in transgenic mice with heart failure.

Transgenic mice overexpressing the inflammatory cytokine tumor necrosis factor (TNF)-alpha (TNF-alpha mice) in the heart develop a progressive heart failure syndrome characterized by biventricular dilatation, decreased ejection fraction, atrial and ventricular arrhythmias on ambulatory telemetry monitoring, and decreased survival compared with nontransgenic littermates. Programmed stimulation in vitro with single extra beats elicits reentrant ventricular arrhythmias in TNF-alpha (n = 12 of 13 hearts) but not in control hearts. We performed optical mapping of voltage and Ca(2+) in isolated perfused ventricles of TNF-alpha mice to study the mechanisms that lead to the initiation and maintenance of the arrhythmias. When compared with controls, hearts from TNF-alpha mice have prolonged of action potential durations (action potential duration at 90% repolarization: 23 +/- 2 ms, n = 7, vs. 18 +/- 1 ms, n = 5; P < 0.05), no increased dispersion of refractoriness between apex and base, elevated diastolic and depressed systolic [Ca(2+)], and prolonged Ca(2+) transients (72 +/- 6 ms, n = 10, vs. 54 +/- 5 ms, n = 8; P < 0.01). Premature beats have diminished action potential amplitudes and conduct in a slow, heterogeneous manner. Lowering extracellular [Ca(2+)] normalizes conduction and prevents inducible arrhythmias. Thus both action potential prolongation and abnormal Ca(2+) handling may contribute to the initiation of reentrant arrhythmias in this heart failure model by mechanisms distinct from enhanced dispersion of refractoriness or triggered activity.

Action Potentials↗

PubMed2006

Loss of alpha2B-adrenoceptors increases magnitude of hypertension following nitric oxide synthase inhibition.

Vascular alpha(2B)-adrenoceptors (alpha(2B)-AR) may mediate vasoconstriction and contribute to the development of hypertension. Therefore, we hypothesized that blood pressure would not increase as much in mice with mutated alpha(2B)-AR as in wild-type (WT) mice following nitric oxide (NO) synthase (NOS) inhibition with N(omega)-nitro-l-arginine (l-NNA, 250 mg/l in drinking water). Mean arterial pressure (MAP) was recorded in heterozygous (HET) alpha(2B)-AR knockout mice and WT littermates using telemetry devices for 7 control and 14 l-NNA treatment days. MAP in HET mice was increased significantly on treatment days 1 and 4 to 14, whereas MAP did not change in WT mice (days 0 and 14 = 113 +/- 3 and 114 +/- 4 mmHg in WT, 108 +/- 0.3 and 135 +/- 13 mmHg in HET, P < 0.05). MAP was significantly higher in HET than in WT mice days 10 through 14 (P < 0.05). Thus blood pressure increased more rather than less in mice with decreased alpha(2B)-AR expression. We therefore examined constrictor responses to phenylephrine (PE, 10(-9) to 10(-4) M) with and without NOS inhibition to determine basal NO contributions to arterial tone. In small pressurized mesenteric arteries (inner diameter = 177 +/- 5 microm), PE constriction was decreased in untreated HET arteries compared with WT (P < 0.05). l-NNA (100 microM) augmented PE constriction more in HET arteries than in WT arteries, and responses were not different between groups in the presence of l-NNA. Acetylcholine dilated preconstricted arteries from HET mice more than arteries from WT mice. Endothelial NOS expression was increased in HET compared with WT mesenteric arteries by Western analysis. Griess assay showed increased NO(x) concentrations in HET plasma compared with those in WT plasma. These data demonstrate that diminished alpha(2B)-AR expression increases the dependence of arterial pressure and vascular tone on NO production and that vascular alpha(2B)-AR either directly or indirectly regulates vascular endothelial NOS function.

Adrenergic alpha-Agonists↗