A comparison of rectal and subcutaneous body temperature measurement in the common marmoset

Correlation of temperature-sensing microchip and rectal temperature measurements in cats

Introduction

Rectal temperature (RT) is the reference standard for clinical evaluation of body temperature in mammals. However, the use of a rectal thermometer to measure temperature can cause stress and other problems, especially in cats. There is a need for clinical techniques that reduce both stress and defensive behavior as part of the provision of better medical care. Subcutaneous temperature-sensing identification microchips fulfil the current legal requirements and provide a reading of subcutaneous temperature (MT).

Methods

The clinical study tried to determine whether there is agreement between MT and RT in normal (n = 58), hospitalized (n = 26) and sedated/anesthetized (n = 36) cats. Three measurements were taken using both methods (MT and RT) in each cat. Correlation between MT and RT, and differences between MT and RT, were estimated for pairs of data-points from the same individual, and all data pairs in each group were considered overall.

Results

There was a strong positive correlation between MT and RT (r = 0.7 to 1.0) (p < 0.0005). The mean differences (d) were always negative and although statistically significant, these d values are likely of no biological importance. The overall d was ‑0.1°C in normal cats (p < 0.0005), -0.1°C in hospitalized cats (p = 0.001) and -0.1°C in sedated/anesthetized cats (p = 0.001). The limits of agreement between MT and RT appear narrow enough for MT to be acceptable estimate of RT. The overall limits of agreement (95%) were ‑0.71°C and 0.53°C (in normal cats); ‑0.51°C and 0.34°C (in hospitalized cats) and ‑0.60°C and 0.42°C (in sedated/anesthetized cats).

Discussion

MT may provide a good alternative to RT measurement in cats. However, this study was mostly performed in animals that were normothermic. Therefore, further studies in larger groups of cats under different conditions are needed to compare trends and assess variation with time.

Use of subcutaneous transponders to monitor body temperature in laboratory rats

Implantable radiofrequency transponders may be adequate for the characterization of hazardous chemicals targeting body temperature control in experimental animals when colonic probes and automated monitoring systems based on intraperitoneal transmitters are not available, installable or applicable for any reason. In this work, we summarize a series of experiments showing the implantation protocol and utility of rice-grain size transponders to monitor subcutaneous temperature (T_sc) after exposure to pharmacological or toxicological treatments targeting body temperature control in laboratory rats. In addition, to explore the responsiveness of this thermometric system, the influence of physiological activity on T_sc readings was examined by monitoring T_sc after a motor exercise in a RotaRod system. Moreover, we characterized the effects of acute oral administration of the pyrethroid insecticide permethrin (PRM) in corn oil (1 mL/kg) on T_sc. PRM has been previously reported to cause dose-related increases in core temperature after administering oral doses ≥75 mg/kg, with peak effects at 2-4 h in adult rats. We monitored T_sc at 30 min intervals over a 4 h period after exposure to PRM (40-160 mg/kg). PRM caused a moderate increase in T_sc starting at ~3.5 h. Overall, T_sc assays showed minimal animal stress (if any) and rapid animal recovery from transponder implantation, simplicity to collect data, convenient testing room space requirements, and a competitive global cost per animal examined. However, various experimental factors may greatly influence the variability within and between individuals, some of which can be controlled by carefully setting up experimental conditions.

A 0.065-mm3 Monolithically-Integrated Ultrasonic Wireless Sensing Mote for Real-Time Physiological Temperature Monitoring

Accurate monitoring of physiological temperature is important for many biomedical applications, including monitoring of core body temperature, detecting tissue pathologies, and evaluating surgical procedures involving thermal treatment such as hyperthermia therapy and tissue ablation. Many of these applications can benefit from replacing external temperature probes with injectable wireless devices. Here we present such a device for real-time in vivo temperature monitoring that relies on "chip-as-system" integration. With an on-chip piezoelectric transducer and measuring only 380 μm × 300 μm × 570 μm, the 0.065-mm³ monolithic device, in the form of a mote, harvests ultrasound energy for power and transmits temperature data through acoustic backscattering. Containing a low-power temperature sensor implemented with a subthreshold oscillator and consuming 0.813 nW at 37 °C, the mote achieves line sensitivity of 0.088 °C/V, temperature error of +0.22/-0.28 °C, and a resolution of 0.0078 °C rms. A long-term measurement with the mote reveals an Allan deviation floor of <138.6 ppm, indicating the feasibility of using the mote for continuous physiological temperature monitoring.

Application of microchip and infrared thermography for monitoring body temperature of beef cattle kept on pasture

The monitoring of body temperature is important for the diagnosis of the physiological state of the animal, being dependent on available methods and their applicability within production systems. This work evaluated techniques to monitor the body temperature of beef cattle kept on pasture and their ability to predict internal temperature. Twenty-three adult bovine females were monitored for six months, and collection data carried out in eleven campaigns (D0-D10) twelve days apart. During collections, the surface temperatures of ear base (ET, ^oC) and ocular globe (OGT, ^oC) were measured by infrared thermography, and the subcutaneous temperature (ST, ^oC) was measured with the use of transponder containing an implantable microchip. Rectal temperature (RT, ^oC) was considered as a reference for body temperature. Temperature and Humidity Index (THI), Black Globe Temperature and Humidity Index (BGHI) and Radiant Heat Load (RHL, W/m²) were calculated. ET (33.32 ± 0.12 °C), ST (36.10 ± 0.07 °C), OGT (37.40 ± 0.06 °C) and RT (38.83 ± 0.03 °C) differed significantly (P˂0.05). There was positive correlation of RT with OGT (r = 0.392), ET (r = 0.264) and ST (r = 0.236) (P˂0.05). Considering the bioclimatic indicators, the highest magnitude correlations were observed between ET and THI (r = 0.71), ET and BGHI (r = 0.65), and ET and RHL (r = 0.48). The use of microchip represented a practical method, but with limited predictability. On the other hand, infrared thermography proved to be safe and non-invasive, presenting greater precision for inference of internal body temperature. ET was more influenced by meteorological conditions.

An Observational Investigation of Behavioral Contagion in Common Marmosets (Callithrix jacchus): Indications for Contagious Scent-Marking

Behavioral contagion is suggested to promote group coordination that may facilitate activity transitions, increased vigilance, and state matching. Apart from contagious yawning, however, very little attention has been given to this phenomenon, and studies on contagious yawning in primates have so far only focused on Old World monkeys and apes. Here we studied behavioral contagion in common marmosets, a species for which group coordination and vigilance are paramount. In particular, we investigated the contagiousness of yawning, stretching, scratching, tongue protrusion, gnawing, and scent-marking. We coded these behaviors from 14 adult marmosets, from two different social groups. During testing sessions, animals were separated into groups of four individuals for 20-min observation periods, across three distinct diurnal time points (morning, midday, and afternoon) to test for circadian patterns. We observed almost no yawning (0.12 yawns/h) and very little stretching behavior. For all other behaviors, which were more common, we found several temporal and inter-individual differences (i.e., sex, age, dominance status) predictive of these responses. Moreover, we found that gnawing and scent-marking, which almost always co-occurred as a fixed-action pattern, were highly temporally clustered within observation sessions. We discuss the relative absence of yawning in marmosets as well as the possible function of contagious scent-marking, and provide suggestions for future research into the proximate and ultimate functions of these behaviors in marmosets.

Body Temperature Monitoring Using Subcutaneously Implanted Thermo-loggers from Holstein Steers

Body temperature (BT) monitoring in cattle could be used to early detect fever from infectious disease or physiological events. Various ways to measure BT have been applied at different locations on cattle including rectum, reticulum, milk, subcutis and ear canal. In other to evaluate the temperature stability and reliability of subcutaneous temperature (ST) in highly fluctuating field conditions for continuous BT monitoring, long term ST profiles were collected and analyzed from cattle in autumn/winter and summer season by surgically implanted thermo-logger devices. Purposes of this study were to assess ST in the field condition as a reference BT and to determine any location effect of implantation on ST profile. In results, ST profile in cattle showed a clear circadian rhythm with daily lowest at 05:00 to 07:00 AM and highest around midnight and rather stable temperature readings (mean±standard deviation [SD], 37.1°C to 37.36°C±0.91°C to 1.02°C). STs are 1.39°C to 1.65°C lower than the rectal temperature and sometimes showed an irregular temperature drop below the normal physiologic one: 19.4% or 36.4% of 54,192 readings were below 36.5°C or 37°C, respectively. Thus, for BT monitoring purposes in a fever-alarming-system, a correction algorithm is necessary to remove the influences of ambient temperature and animal resting behavior especially in winter time. One way to do this is simply discard outlier readings below 36.5°C or 37°C resulting in a much improved mean±SD of 37.6°C±0.64°C or 37.8°C±0.55°C, respectively. For location the upper scapula region seems the most reliable and convenient site for implantation of a thermo-sensor tag in terms of relatively low influence by ambient temperature and easy insertion compared to lower scapula or lateral neck.

Microchip transponder thermometry for monitoring core body temperature of antelope during capture

Hyperthermia is described as the major cause of morbidity and mortality associated with capture, immobilization and restraint of wild animals. Therefore, accurately determining the core body temperature of wild animals during capture is crucial for monitoring hyperthermia and the efficacy of cooling procedures. We investigated if microchip thermometry can accurately reflect core body temperature changes during capture and cooling interventions in the springbok (Antidorcas marsupialis), a medium-sized antelope. Subcutaneous temperature measured with a temperature-sensitive microchip was a weak predictor of core body temperature measured by temperature-sensitive data loggers in the abdominal cavity (R(2)=0.32, bias >2 °C). Temperature-sensitive microchips in the gluteus muscle, however, provided an accurate estimate of core body temperature (R(2)=0.76, bias=0.012 °C). Microchips inserted into muscle therefore provide a convenient and accurate method to measure body temperature continuously in captured antelope, allowing detection of hyperthermia and the efficacy of cooling procedures.

Measurement of body temperature in 300 dogs with a novel noncontact infrared thermometer on the cornea in comparison to a standard rectal digital thermometer

OBJECTIVE

To assess the accuracy of obtaining body temperatures in dogs with a noncontact infrared thermometer (NCIT) on the cornea compared with a rectal digital thermometer (RDT).

DESIGN

Prospective single center study.

SETTING

University teaching hospital.

ANIMALS

Three hundred dogs presented with low, normal, or high body temperatures.

INTERVENTIONS

Three body temperature readings were measured by an RDT and by an NCIT on the cornea of the left eye by 2 investigators (experienced and inexperienced). Results obtained by the 2 methods were compared.

MEASUREMENTS AND MAIN RESULTS

Median body temperature measured by the experienced investigator with the RDT and the NCIT were 38.3°C (range 35.5°C-41.1°C; 95% CI: 38.2-38.4°C) and 37.7°C (35.9°C-40.1°C; 95% CI: 37.7°C-37.9°C), respectively. Measurement of RDT as well as of NCIT correlated well between both investigators (rRDT = 0.94; rNCIT = 0.82; respectively, P < 0.001 for both methods). Mean RDT and NCIT-temperature correlated poorly (r = 0.43; P < 0.001) when taken by the experienced investigator and even less by the nonexperienced investigator (r = 0.38; P < 0.001). Repeatability of the NCIT revealed an unsatisfactory value (0.24°C) compared to RDT measurement (0.12°C). Agreement between both devices in measuring low, normal, and high values, calculated by Cohens-Kappa, was unsatisfactory (к = 0.201; P < 0.001). Calculating the receiver operating characteristic curve to determine the best threshold for fever (defined as RDT temperature >39.0°C) showed an area under the curve of 0.76. Mean discomfort score was significantly lower using NCIT compared to RDT measurement (P < 0.001).

CONCLUSIONS

There was poor agreement between body temperatures obtained by RDT and NCIT. The corneal NCIT measurement tends to underrecognize hypothermic and hyperthermic conditions. Although the use of the NCIT yields faster results and is significantly more comfortable for the dog than the RDT measurement, it cannot be recommended in dogs at this time.

Comparison of body temperature readings between an implantable microchip and a cloacal probe in lorikeets (Trichoglossus haematodus sp.)

Body temperature readings can be a useful diagnostic tool for identifying the presence of subclinical disease. Traditionally, rectal or cloacal thermometry has been used to obtain body temperatures. The use of implantable microchips to obtain these temperatures has been studied in a variety of animals, but not yet in avian species. Initially, timepoint one (T₁), nine lorikeets were anesthetized via facemask induction with 5% isoflurane and maintained at 2-3% for microchip placement and body temperature data collection. Body temperature was measured at 0 and 2 min post-anesthetic induction both cloacally, using a Cardell veterinary monitor and also via implantable microchip, utilizing a universal scanner. On two more occasions, timepoints two and three (T₂, T₃), the same nine lorikeets were manually restrained to obtain body temperature readings both cloacally and via microchip, again at minutes 0 and 2. There was no statistical difference between body temperatures, for both methods, at T₁. Microchip temperatures were statistically different than cloacal temperatures at T₂ and T₃. Body temperatures at T₁, were statistically different from those obtained at T₂ and T₃ for both methods. Additional studies are warranted to verify the accuracy of microchip core body temperature readings in avian species.

Optimization of a pain model: effects of body temperature and anesthesia on bladder nociception in mice

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating urological condition that is resistant to treatment and poorly understood. To determine novel molecular treatment targets and to elucidate the contribution of the nervous system to IC/BPS, many rodent bladder pain models have been developed. In this study we evaluated the effects of anesthesia induction and temperature variation in a mouse model of bladder pain known as urinary bladder distension (UBD). In this model compressed air is used to distend the bladder to distinct pressures while electrodes record the reflexive visceromotor response (VMR) from the overlying abdominal muscle. Two isoflurane induction models are commonly used before UBD: a short method lasting approximately 30 minutes and a long method lasting approximately 90 minutes. Animals were anesthetized with one of the methods then put through three sets of graded bladder distensions. Distensions performed following the short anesthesia protocol were significantly different from one another despite identical testing parameters; this same effect was not observed when the long anesthesia protocol was used. In order to determine the effect of temperature on VMRs, animals were put through three graded distension sets at 37.5 (normal mouse body temperature), 35.5, and 33.5°C. Distensions performed at 33.5 and 35.5°C were significantly lower than those performed at 37.5°C. Additionally, Western blot analysis revealed significantly smaller increases in spinal levels of phosphorylated extracellular-signal regulated kinase 2 (pERK2) following bladder distension in animals whose body temperature was maintained at 33.5°C as opposed to 37.5°C. These results highlight the significance of the dynamic effects of anesthesia on pain-like changes and the importance of close monitoring of temperature while performing UBD. For successful interpretation of VMRs and translation to human disease, body temperature should be maintained at 37.5°C and isoflurane induction should gradually decrease over the course of 90 minutes.

Assessment of the use of temperature-sensitive microchips to determine core body temperature in goats

Body temperature was measured at five different body sites (retroperitoneum, groin, semimembranosus muscle, flank and shoulder) using temperature-sensitive microchips implanted in five female goats, and compared with the core body and rectal temperatures. Body temperature was measured while the goats were kept in different ambient temperatures, with and without radiant heat, as well as during a fever induced experimentally by injection of bacterial lipopolysaccharide. Bland-Altman limit of agreement analysis was used to compare the temperature measurements at the different body sites during the different interventions. Temperatures measured by the microchip implanted in the retroperitoneum showed the closest agreement (mean 0.2 °C lower) with core and rectal temperatures during all interventions, whereas temperatures measured by the microchips implanted in the groin, muscle, flank and shoulder differed from core body temperature by up to 3.5 °C during the various interventions.

The potential for microchip-automated technology to improve enrichment practices

The greatest limitation involved with providing enrichment and evaluating its effects on captive mammals is a lack of available staff time [Hoy et al., 2009]. One method to overcome this is through the use of automated husbandry systems to dispense enrichment to individual animals by using implantable radio frequency microchips. An international multi-institutional survey was conducted to determine whether the personnel involved with management, research, and husbandry of captive mammals would support the development of such automated husbandry systems. The survey was also designed to establish which applications of the system would be considered to be most beneficial. Overall, there was a very high level of interest by survey respondents in adopting automated husbandry systems and all potential applications were considered beneficial to varying degrees. These results, together with the relatively low cost of installation and operation, demonstrate that in the future automated enrichment could be an important and effective means of enhancing captive animal management.

A study on the applicability of implantable microchip transponders for body temperature measurements in pigs

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.

A cardiovascular monitoring system in conscious cynomolgus monkeys for regulatory safety pharmacology

INTRODUCTION

This project addresses the validation study design of a test system using a telemetered non-human primate model for cardiovascular safety pharmacology evaluation.

METHODS

The validation provided by the supplier evaluated installation (IQ) and operation (OQ) qualifications. This protocol was completed with tests evaluating electronic data management and accuracy and precision of transmitter (n=4) measurements for temperature and pressure criteria with a series of tested values. As part of performance qualification, physical activity (for 24 h) as well as cardiovascular, ECG (20 complexes for each animal) and systemic arterial blood pressure (SAP, 10 different measures), data were recorded simultaneously from the same animals (n=4) using certified equipment and the telemetry system. Reliability was evaluated over 60 days.

RESULTS

The IQ and OQ were completed successfully. The electronic data management was performed successfully. The ex-vivo evaluation for temperature and pressure showed high correlation (R(2)>0.99) but with a slight pressure shift, as expected, with this transmitter model. For physical activity, the correlation coefficients were good to excellent with high activity counts but the comparison demonstrated a limited sensitivity of the telemetry system with animal presenting low activity levels. ECG interval measurement using the telemetry software was considered at least equivalent to manual measurement, but with some limitations in the reading of the ECG. The comparison between both methods of SAP measurement showed adequate precision (R(2)=0.969) but no accuracy.

DISCUSSION

Reference monitoring methods are important to ensure proper test system validation. Monitoring with a reference methodology and the telemetry system is important in order to evaluate precision and accuracy of the test system. Computerized analysis may lack the capability to analyze ECG complexes with abnormal morphologies. This reinforces the need to have ECG evaluation prior to telemetry implantation along with visual evaluation of ECG tracing at standard speed (e.g. 50 mm/s) at all time points.

A comparison of non-contact, subcutaneous, and rectal temperatures in captive owl monkeys (Aotus sp.)

BACKGROUND

Three methods of body temperature measurement were compared in owl monkeys: non-contact infrared thermometry, subcutaneous transponder, and rectal probe.

METHODS

Forty owl monkeys (Aotus sp.) were used. Animals were implanted with subcutaneous microchip transponders. Infrared thermometry was used at three different sites. All measurements were taken and repeated randomly.

RESULTS

Infrared and subcutaneous measurements did not agree well with rectal thermometry. Subcutaneous and rectal temperatures were highly repeatable, and subcutaneous temperatures were most agreeable to rectal temperatures.

CONCLUSIONS

Further investigation is needed into subcutaneous implant sites and use of different infrared thermometers in this species.

Refinement of the use of non-human primates in scientific research. Part III: refinement of procedures

There is an ethical and scientific need to minimise the harm experienced by animals used in scientific procedures and to maximise their well-being. Welfare can be improved by the refinement of practice, particularly if these refinements are applied to every aspect of the life of an animal used in the laboratory, from birth to death. Primates are considered likely to have a greater capacity for suffering than other sentient species and therefore refinement of their use is particularly important. The refinement of the human impact on laboratory-housed primates and of housing and husbandry practices are dealt with in parts I and II of this three-part review. In part III, methods of refinement that can be applied specifically to the use of primates in procedures, are summarised and discussed, together with a description of some current practices, and the scientific evidence that suggests that they should no longer be used. Methods of refinement of identification, capture and restraint, sampling, administration of substances, humane endpoints, and euthanasia are included. If these methods are used, taking into account species-specific differences and needs, it is concluded that harm can be minimised and primate welfare improved.

The safety and immunogenicity of Bacillus Calmette-Guérin (BCG) vaccine in European badgers (Meles meles)

European badgers (Meles meles) are a wildlife reservoir for Mycobacterium bovis (M. bovis) in Great Britain (GB) and the Republic of Ireland and therefore constitute a potential source of infection for cattle. Reduction of badger densities in the Republic of Ireland has resulted in an associated reduction in the risk of a herd break-down with bovine tuberculosis and a study to determine whether this is also the case in GB has been running since 1997. If badgers are a significant source of M. bovis infection for cattle, vaccinating badgers with Bacillus Calmette-Guérin (BCG) might prove to be a long term, cost-effective strategy for controlling bovine tuberculosis whilst preserving badger populations. As a first step towards BCG vaccination of wild badgers, it was necessary to demonstrate safety of the vaccine in captive badgers. Therefore, captive badgers were vaccinated with a commercial source of BCG that is already licensed for administration to humans in GB-BCG Danish SSI. Using a protocol prescribed by the Veterinary Medicines Directorate (VMD) of GB, badgers were vaccinated with two consecutive doses of BCG via either the subcutaneous (s.c.) or intra-muscular (i.m.) routes. The first dose was high, ranging from 16 to 22 x 10(7) colony-forming units (CFU), and was followed 15 weeks later by a lower dose in the range of 4-7 x 10(5)CFU. Local reaction at the site of injection and general responses (body temperature, haematology and blood serum chemistry), behaviour and excretion of BCG were monitored for 28 weeks from the time of the first vaccination. The only side-effect observed was the occurrence of localised swelling at the site of BCG injection that disappeared 48 days after i.m. vaccination but persisted longer in the group vaccinated by the s.c. route. Immunological responses were measured at regular intervals. Strong cellular responses were observed 13 days after the first vaccination, which persisted for 76 days. The lower dose induced a weaker and shorter-lived response.

Effect of 5-HT1B/D receptor agonist and antagonist administration on motor function in haloperidol and MPTP-treated common marmosets

An interaction between brain serotonergic and dopaminergic systems involving 5-HT(1B) receptors may contribute to motor complications arising from the drug treatment of neurological and psychiatric disorders. This study assessed the effects of treatment with a non-selective 5-HT(1B/D) receptor agonist and a selective 5-HT(1B) receptor antagonist on akinesia induced in marmosets by long-term treatment with haloperidol and on motor disability and l-3, 4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated marmosets. In marmosets treated chronically with haloperidol, the 5-HT(1B) agonist SKF-99101-H reduced locomotor activity and induced motor disability, whereas the 5-HT(1B) antagonist SB-224289-A had no effect on motor behaviour. Haloperidol administration induced a suppression of locomotor activity which was not reversed by co-administration of either SKF-99101-H or SB-224289-A. In MPTP-treated common marmosets, neither SKF-99101-H nor SB-224289-A induced any significant change in motor function. However, SKF-99101-H inhibited L-DOPA-induced dyskinesia and the reversal of motor deficits whereas SB-224289-A was without effect. The results of this study indicate that the 5-HT(1B) receptor appears not to be an appropriate target for the treatment of Parkinson's disease (PD) or for the control of drug-induced motor complications developed as a tong-term consequence of neuroleptic or L-DOPA treatment.

4-Methylthioamphetamine-induced hyperthermia in mice: influence of serotonergic and catecholaminergic pathways

4-Methylthioamphetamine (4-MTA), also known as p-methylthioamphetamine, is a new amphetamine derivative which in humans has been increasingly associated with severe intoxications and several deaths. As hyperthermia is considered to be one of the most life-threatening acute physiological consequences of amphetamine-related intoxications, it was our aim to determine whether 4-MTA induces changes in body temperature in a mouse model. Accordingly, we measured the subcutaneous temperature after acute administration of 4-MTA in CD1 mice. Because hyperthermia seems to result from the central and peripheral actions of catecholamines and serotonin (5-hydroxytriptamine or 5-HT), we also investigated the possible interactions of some catecholaminergic and serotonergic receptor blockers and the inhibition of monoamine oxidase (MAO) with this effect. 4-MTA induced hyperthermia in CD1 mice. Blockade of the 5-HT receptors with methysergide and MAO inhibition with pargyline resulted in the potentiation of the 4-MTA-induced hyperthermic effect. Blockade of the alpha(1)-adrenergic receptors with prazosin completely reverted the 4-MTA-induced hyperthermia while with the beta-adrenergic receptor blocker dl-propranolol this reversal was not complete. Blockade of the alpha(2)-adrenergic receptors with yohimbine had no effect on the hyperthermia induced by 4-MTA. These results suggest that 4-MTA-induced hyperthermia is highly influenced by the catecholaminergic and serotonergic receptor activation and the MAO activity.

Physostigmine and hyoscine improves protection against the lethal and incapacitating effects of nerve agent poisoning in the guinea-pig

This study is drawn from a work programme aimed at developing improved medical counter measures for nerve agent poisoning. Guinea-pigs were administered pyridostigmine (5.1 microg/h) or physostigmine (4.7 microg/h) and hyoscine (1.94 microg/h) for 6 days via a subcutaneously implanted mini osmotic pump. Pyridostigmine inhibited red cell acetylcholinesterase (AChE) by 44.2 +/- 2.7% and plasma cholinesterase (ChE) by 29.9 +/- 1.8%. Physostigmine and hyoscine inhibited red cell AChE by 18.7 +/- 3.7% and plasma ChE by 44.1 +/- 3.1%. On day 6, animals were challenged with a lethal dose of tabun (GA; 125 microg/kg), sarin (GB; 51.2 microg/kg), soman (GD; 31.2 microg/kg), GF (50 microg/kg) or VX (11.25 microg/kg) administered by the subcutaneous route. Animals were closely observed for signs of poisoning. The time to the onset of signs of poisoning was similar for all the agents except for VX, which showed a delay compared to the other agents. Following pretreatment with either pyridostigmine or physostigmine and hyoscine most animals survived for 2-3 h following nerve agent administration. In contrast, only physostigmine and hyoscine prevented or reduced the duration of the signs of incapacitation and the temperature drop produced by all the agents. Pyridostigmine-pretreated animals showed little or no recovery from incapacitation prior to death. Physostigmine and hyoscine pretreatment provided statistically (P < 0.05) better protection against GB, GD and VX lethality (24 h) than pyridostigmine pretreatment and better protection against GA and GF lethality.

Development of telemetry system in the common marmoset--cardiovascular effects of astemizole and nicardipine

The purpose of this study was to evaluate a telemetry system for examining the cardiovascular system in the conscious common marmoset. Parameters obtained were blood pressure, heart rate, respiratory rate, ECG, body temperature and locomotor activity, and these were continuously recorded on a data recorder via the telemetry system and then processed by a computerized system. Diurnal rhythms of blood pressure, heart rate, body temperature and locomotor activity were observed in this system. We studied the effects of astemizole (antihistamine) and nicardipine (Ca2+ channel blocker) on cardiovascular parameters. Astemizole at 30 mg/kg (p.o.) and at 1 to 3 mg/kg (i.v.), prolonged QT interval and induced ventricular extrasystole. Torsades de pointes occurred in one of three cases at 3 mg/kg (i.v.) and 30 mg/kg (p.o.), while it did not affect the blood pressure, respiratory rate and body temperature. Nicardipine at 30 mg/kg (p.o.) caused sustained hypotension and tachycardia. These results demonstrate the usefulness of the telemetry system using the common marmoset for evaluating the cardiovascular effects of drugs under physiological conditions.