Ghanta N. Rao et.al., Toxicologic Pathology (1990) 18, p412 t/m 417

Abstract :

Long-term toxicity and carcinogenity studies require positive identification of animals. Due to the unreliability of traditional methods, it was necessary to investigate more dependable identification methods that can be read directly or by electronic means. A two-year study to determine the stability of and tissue reaction to a microchip glass-sealed device implanted in subcutaneous tissue of mice was conducted. Seventy B6C3F1 mice of each sex were anaesthetised and implanted with the microchip. The devices were read by an electronic detector and palpated at periodic intervals. Ten mice of each sex were necropsied at 3 and 15 months with the remaining animals necropsied at 24 months. Of the 140 devices implanted, 3 were lost and 4 failed during the 24 months study. Devices were palpable and appeared to be fixed at one location with no obvious swelling due to inflammation or palpable masses around the implants for 24 months. At the 3, 15 and 24 month necropsies, implants were encapsulated by connective tissue. Light microscopic evaluation indicated that the capsule around the implants was thin and composed of fibrocytes and mature collagen fibres, with minimal to mild inflammation and occasional granulomatous reaction. Neoplastic changes were not observed in the tissue around the glass-sealed devices with polypropylene cap for up to 24 months.

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Evaluation of a microchip implant system used for animal identification in rats

D.H. Ball et.al., Laboratory Animal Science (1991) 41, p185, 186

Abstract :

A 1-year study was undertaken in rats to evaluate a microchip-based animal identification system (BioMedic Data Systems, Inc., Seaford DE, USA). Each animal was implanted with a miniature radio transponder that was capable of transmitting a unique identification number. The system provided proper identification of each animal and permitted data to be added automatically to a computer data base file.
The implanted transponders produced no adverse clinical or histopathological side effect in rats.

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Microchip implant system used for animal identification in laboratory rabbits, guineapigs, woodchucks and in amphibians

Margund Mrozek et.al., Laboratory Animals (1995) 29, p339-344

 Abstract :

Traditional methods for animal identification have a number of drawbacks. We evaluated a new system for individual identification using microchip implants in rabbits, guineapigs, woodchucks and amphibians. Implantation procedure and long-term observations are described.
Microchip implants proved to be a practicable and reliable system for animal identification without obvious adverse effects. The applicability of electronic animal identification in comparison with common methods and with regard to animal welfare and legal aspects is discussed.

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A microchip implant system as a method to determine body temperature of terminally ill rats and mice

W.J. Kort et.al., Laboratory Animals (1998) 32, p260-269

Abstract :

In a series of experiments, Klebsiella pneumoniae was innoculated intratracheally into rats and mice, and the temperature of the animals was recorded twice daily using microchip transponders. Transponders are interrogated by radio frequencies and were implanted either subcutaneously or intraperitoneally. The microchip temperatures were compared with rectal temperatures taken at the same time. The purpose of the experiments was (a) to investigate the practicability and reliability of ELAMS^tm for temperature recording, (b) to compare values given by subcutaneously and intraperitoneally implanted transponders with rectal temperatures, and (c) to determine a 'temperature-cut-off' point as an alternative for 'death of the animal' as an end point for the experiment.
The results showed that ELAMS was easy to operate and no important drawbacks in the use of the system were observed. The temperatures generated by the transponders implanted subcutaneously and intraperitoneally did not differ significantly from rectal temperatures. In two out of three experiments on rats, it was shown that when temperatures reached values below 36 degr. C, the medical survival time of the animals was 24h. In the one experiment on mice the same median survival time was observed at 36 degr. C. In one experiment using rats however, the disease was so acute that death occured before any temperature drop was seen.
The results show that when a 36 degr. C cut-off point is used instead of the time of death in this particular animal model, the statistical analysis was not altered, but that it would spare animals further suffering for approximately 24h. The argument that measuring body temperature is a laborious job and stressful to the animal is overcome when the ELAMS system is used.

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A mechanism for the inhibition of fever by a virus

Antonio Alcami and Geoffrey L. Smith, Proc. Natl. Acad. Sci. USA, vol 93, pp. 11029-11034, Oct 1996

 Abstract :

Poxviruses encode proteins that block the activity of cytokines. Here we show that the study of such virulence factors can contribute to our understanding of not only virus pathogenesis but also the physiological role of cytokines. Fever is a nonspecific response to infection that contributes to host defense. Several cytokines induce an elevation of body temperature when injected into animals, but in naturally occuring fever it has been difficult to show that any cytokine has a critical role. We describe the first example of the supression of a fever by a virus and the molecular mechanism leading to it. Several vaccinia virus strains including smallpox vaccines express soluble interleukin 1 (IL-1) receptors, which bind IL-1 beta but not IL-1 alpha. These viruses prevent febrile response in infected mice, whereas strains that naturally or through genetic enginering lack receptors induce fever. Repair of the defective IL-1 beta inhibitor in the smallpox vaccine Copenhagen, suppresses fever and attenuates the disease. The vaccinia-induced fever was inhibited with antibodies to IL-1 beta. These findings provide strong evidence that IL-1 beta, and not other cytokines, is the major endogenous pyrogen in a poxvirus infection.

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

J. Cilia et al., Journal of Pharmacological and Toxicological Methods 40, 21-26 (1998)

 Abstract :

Two methods of measuring body temperature were compared in common marmosets. Subcutaneous temperatures were measured remotely via previously implanted subcutaneous microchips (PLEXX bv, IPTT-100) prior to measurement of rectal temperature using a conventional rectal probe. Marmosets were treated with saline or the brain penetrant 5-HT1_A/B/D receptor agonist SKF-99101H (0.3-3 mg/kg SC), which has previously shown to induce hypothermia in guineapigs. Body temperature was sampled immediately before drug administration and at 30 minute intervals thereafter for a period of 2.5 h.
SKF-99101H dose-dependently induced hypothermia in the common marmoset and there was close agreement between rectal and subcutaneous body temperatures, with an average difference in absolute body temperature of 0.26 ± 0.02 degr. C. The data show that subcutaneously implanted microchips provide a simple reliable measure of body temperature in common marmosets which is sensitive to pharmocological intervention, minimises handling induced stress, and is minimally invasive.

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Use of an implantable Device to monitor body temperature in research swine.

S. Dunney et al., Contempory Topics in Laboratory Animal Science 36 (4):62, 1997

 Abstract :

Conducting research with animal models often requires the handling of test subjects multiple times in a day for such procedures as administering treatments or taking body temperature. This is especially troublesome when conducting research with swine, which are particularly prone to stress from handling. Research has shown that pigs under stress have reduced immunological function due to increased level of serum cortisol. This may affect many test parameters including the blood profile, serum chemistry, and even body temperature itself. Minimising the duration of handling and restraint of the test animals benefits the animals psychologically, aids in protecting the integrity of the data, and is a human safety measure since swine can be quite difficult to handle. The historical method in this laboratory for taking core body temperature of pigs has been the use of rectal thermometers. A digital infant thermometer is inserted in the rectum and held there for as much as three minutes. To perform this procedure, the animal must be captured and manually restrained for a relatively long period of time. A new method was developed for taking the core temperature in under five seconds. The Pocket Scanner^tm (BioMedic Data Systems, Seaford DE, USA) with IPTT-100 transponder implants was designed for use in small laboratory animals. This commercially available system consists of a small implantable transmitting device and a wand-type reader with a digital display. When the implant is placed in an approriate area of the body, it emits a constant signal containing information on core body temperature and animal identification number. Using a 12 gauge implanting needle, implants are injected into the animal to a depth of approximately 1 cm, immediately lateral and slightly dorsal to the anus. The reader is touched to the implant site, and the temperature is displayed in five seconds.
To test the accuracy of this device in swine, temperature of ten pigs weighing approximately 20 kg, were taken with both rectal thermometer and scanner for ten days. The animals received a bacterial challenge for a separate infectious disease trial on day 0, causing elevation in temperature. After comparing the values from each device, we found that the scanner closely followed the rectal thermometer in accuracy and was therefore acceptable to use in our discovery research trials.

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Comparison of body temperatures of goats, horses and sheep measured with a tympanic infrared thermometer, an implantable microchip transponder, and a rectal thermometer.

 Abstract :

Body temperature of goats, horses, and sheep was measured, using 3 methods. Tympanic temperature was measured with a tympanic infrared thermometer, subcutaneous temperature was measured with an implantable microchip transponder, and rectal temperature was measured with a digital thermometer. For goats, rectal and subcutaneous temperatures were significantly higher than tympanic temperatures, but rectal and subcutaneous temperatures did not differ significantly. For horses and sheep, rectal temperatures were significantly higher than tympanic and subcutaneous temperatures were significantly higher than subcutaneous temperatures. Tympanic infrared thermometry correlated well with traditional rectal thermometry in goats and sheep and should be considered as a viable alternative in those species. Additionally, implantable microchip transponders in goats could be used, because those temperatures also correlated well with temperatures derived by rectal thermometry. Due to the poor correlation with rectal thermometry and reaction of some animals to insertion of the tympanic probe, neither of the alternative methods appear to be useful in horses at this time.
Tympanic infrared thermometers and implantable microchip transponders were convenient to use and allowed temperature measurements to be obtained more rapidly than when thermometers were used

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