Temperature Of Rabbits Research Articles

Theileria annulata: Its Propagation in Rabbits for the Attenuation of Piroplasms in Cross-Bred Calves.

Simple SummaryTicks and tick-borne diseases (TTBDs) are major hindrances for the growth and development of the livestock industry. Among TTBDs, theileriosis has the most important disease-causing high morbidity, mortality, and productive and reproductive losses in cattle. These parasites are mainly present in tropical and sub-tropical areas of the world, where they primarily infect ruminants. The current study was primarily aimed to attenuate the T. annulata in rabbits and to check its severity in susceptible cross-bred calves. Moreover, a comparison between experimentally infected and tested calves was also conducted. The significant rise in temperature and the percentage of infected cells were observed in the rabbits’ post-inoculation. All the infected calves showed a significant rise in temperature, piroplasm parasitemia %age, and lymph node enlargement, while the inoculated calves showed a slight rise in temperature, no piroplasm, and no enlargement of lymph nodes during the whole trial.Tropical theileriosis caused by the protozoan; Theileria annulata is a tick-borne disease (TBD) transmitted by ticks of genus Hyalomma; is clinically characterized by fever, anemia, and lymphadenopathy; and is responsible for heavy economic losses in terms of high morbidity and mortality rates with reduced production. Infected red blood cells of T. annulata were inoculated into rabbits intraperitoneally, and propagation of T. annulata has been investigated. The current study has shown an association between induced tropical theileriosis and variation of body temperature in rabbits. A significant rise in temperature (39.92 ± 0.33 °C) was seen on day 8 onwards, with the maximum temperature (40.27 ± 0.44 °C) on day 14 post-inoculation. In the current study, in vivo trials in susceptible cross-bred calves to investigate the attenuation and comparison with the infected group were also conducted. All the infected calves (n = 5) showed a significant rise in temperature (40.26 ± 0.05 °C) on day 10 onwards, with the maximum temperature (40.88 ± 0.05 °C) on day 16. The temperature of inoculated calves increased gradually post-inoculation, but the difference was not significant. A maximum parasitemia of 20% was observed in infected calves, but no piroplasm parasitemia was observed in inoculated calves. The prescapular lymph nodes of infected calves were enlarged, while the lymph nodes of inoculated calves remained normal throughout the trial. Analysis of clinical and parasitological responses of infected and inoculated calves showed a significant difference (p ≤ 0.05) in terms of temperature, parasitemia, and lymph node scoring between two groups. The current study was primarily aimed to attenuate T. annulata in rabbit and to check its virulence in susceptible calves. It is concluded that propagation of Theileria annulata in rabbits made it attenuated. Rabbit can be used as an in vivo model to weaken the virulence of T. annulata.

Доклиническая оценка лечения на модели хронического остеомиелита у кроликов

Introduction. Chronic osteomyelitis is one of the problems in orthopedic surgery. Recently, in the treatment of chronic osteomyelitis, biodegradable materials are increasingly used as a local antibiotic carrier. In our study, we used bone allograft, which prepared by Marburg system. The purpose of the study was to evaluate preclinical changes of use the antibiotic-impregnated bone allograft on osteomyelitis model in rabbit. Materials and methods. Osteomyelitis was caused in rabbits by the human strain Staphylococcus aureus, which is introduced into bone defects created in the distal femur. Three groups were selected depending on the filling: group 1 - antibiotic impregnated biodegradable material “PerOssal”, group 2 –whole bone allograft soaked in antibiotic, group 3 - perforated bone allograft soaked in antibiotic. We used a clinical examination for the evaluating decreasing of chronic osteomyelitis process.Results. The body temperature of all experimental animals was measured with a non-contact thermometer during the entire observation period, which was 42 days. The average temperature in rabbits in groups before surgery was 36.90 in-group 1; in-group 2 - 36.40; in-group 3 - 36.20. On the first day after the operation, in groups 1 and 3, there was no significant difference with the initial body temperature in rabbits before the operation, while in-group 2, the body temperature on the first day after the operation was 39.00. In the early postoperative period, the maximum increase in body temperature is observed on the 3rd day in-group 1 up to 39.20 and in-group 3 38.20. In-group 2, the maximum rise in temperature was on the 2nd day after surgery up to 38.60. The average weight in operated rabbits before surgery was 2983.3 g in-group 1; in-group 2 - 3206.7 gr; in-group 3 - 2300.0 gr. In the 1st group in the postoperative period in the 1st group there is a deficit on the early postoperative day amounted to 1.3 g in dynamics decreased up to 5 days and then there was a stable increase in weight, which in general by the 42nd day was 783, 4 grams. In-group 2, on the first day, there was a maximum body weight deficit of up to 92.3 g, with a subsequent increase, and in general, for the entire observation period, the increase was 200 g. In-group 3, on the first postoperative day, the body weight deficit was 13.9 grams. In the dynamics, there was a slight instability in weight, for example, on day 5, body weight was 3284.6 g, with a decrease on day 6 to 3169.2 g. Visually assessing the wound in-group 1, wound suppuration, divergence or instability of the sutures were not noted. In-group 3, on the 28th day after the operation, there was a slight infiltration of soft tissues in the area after the surgical wound. In the 2nd group on the 14th day there was a slight infiltration of soft tissues in the area after the surgical wound, and on the 28th and 42nd days there was suppuration of the postoperative wound.Conclusion. Thus, in this study we showed, that perforated bone allograft is an available biomaterial can be used in bone regenerative surgery.Key words: Preclinical evaluation algorithm, chronic osteomyelitis, rabbits model, preclinical study

Effect of theatre temperature on body temperature during anaesthesia for routine neutering of domestic rabbits (Oryctolagus cuniculus)

ObjectiveTo investigate the effect of theatre temperature on body temperature in rabbits undergoing castration or ovariohysterectomy surgery during general anaesthesia. Study designProspective, clinical study. AnimalsA group of 88 rabbits presented for elective neutering. MethodsRabbits were divided into male (31/54) and female (23/54) groups and assigned to one of two theatre temperatures via coin toss. Theatre temperature was 23 °C (±2 °C) for group A (n = 37/54) and 28 °C (±2 °C) for group B (n = 17/54). During anaesthesia and recovery, theatre temperature and rectal temperature were recorded every 5 minutes. Time to resumption of feeding and passing faeces were recorded. Data are presented as median (interquartile range) or mean (± standard deviation). Statistical analyses comprised a mixed-effects model, with Sidak’s multiple comparison test for post-hoc testing and Fisher’s exact test; p < 0.05. ResultsA total of 54 rabbits completed the study, with median age 6 (4–9) months and median weight 1.53 (1.30–1.79) kg. In rabbits undergoing castration, theatre temperature did not significantly affect body temperature. Mean temperatures immediately after induction were 38.6 °C and 38.7 °C and at the end of the procedure 38.5 °C and 38.5 °C for group A and group B, respectively. In rabbits undergoing ovariohysterectomy, mean temperatures immediately after induction were 38.3 °C and 38.8 °C and at the end of the procedure 38.1 °C and 39.2 °C for group A and group B, respectively. Rabbits undergoing ovariohysterectomy at an ambient temperature of 28 °C had a significantly higher final temperature, mean ± 1.15 °C (95% confidence interval, 0.47–1.83), compared with 23 °C (p = 0.001). Theatre temperature did not affect return to feeding or defaecating. Conclusions and clinical relevanceDuring anaesthesia an ambient theatre temperature of 28 °C may reduce the risk of hypothermia in rabbits undergoing ovariohysterectomy or similarly invasive surgery.

Lung cancer photothermal ablation by low-power near-infrared laser and topical injection of indocyanine green.

Surgical treatment is the gold standard for the treatment of early-stage non-small-cell lung cancer. However, minimally invasive tumour ablation can be an alternative treatment for patients not eligible for surgery due to comorbidities. The aim of this study was to evaluate the efficacy of photothermal ablation therapy using low-power near-infrared laser and topical injection of indocyanine green (ICG), a photosensitizer, in a preclinical study using a rabbit VX2 lung cancer model. Six New Zealand white rabbits were used. Five hundred microlitres of a suspension containing 0.5 × 107 VX2 cancer cells with growth factor-reduced Matrigel was inoculated into the right lung using an ultrathin bronchoscope. Three rabbits were treated with laser ablation therapy with topical injection of ICG, whereas another 3 rabbits were treated with laser ablation alone. All tumours were irradiated with a laser with 500-mW output at 808 nm for 15 min. The tumours were examined histopathologically to assess the state of ablation. The maximum tumour surface temperatures in rabbits treated using ICG/laser and laser alone were higher than 58°C and lower than 40°C, respectively. The ablated areas in the rabbits treated with ICG/laser were significantly larger than those in the rabbits treated with laser alone (0.49 ± 0.27 vs 0.02 ± 0.002 cm2, respectively) (P < 0.05). The photothermal treatment using the combination of low-power near-infrared laser and topical injection of ICG can ablate a larger tumour area than laser treatment alone.

Effect of premedication with subcutaneous adrenaline on the pharmacokinetics and immunogenicity of equine whole IgG antivenom in a rabbit model

Subcutaneous administration of a low dose of adrenaline is used to prevent the early adverse reactions (EARs) induced by snake antivenoms. We used a rabbit model to study the effect of premedication with adrenaline on the potential of antivenoms to exert therapeutic effects and to induce late adverse reactions. We found that premedication with adrenaline did not change the heart rate or blood pressure of normal rabbits, but reduced the rise in temperature in rabbits previously sensitized with antivenom. Pharmacokinetic studies suggest that premedication with adrenaline does not affect the ability of the antivenom to exert the initial control of envenomation nor the susceptibility of rabbits to develop recurrence of antigenemia and envenomation. Our results also indicate that it is unlikely that premedication with adrenaline decreases the incidence of late reactions induced by the antivenom administration, although it reduces the extent of early reactions.

Antiendotoxin effect of Jinhuaqingre capsules

Objective: To investigate the anti-pyretic and anti-endotoxin effect of Chinese herb medicine Jinhuaqingre capsules. Methods: Thirty healthy male New Zealand rabbits with lipopolysaccharide-induced fever were divided into 5 groups (6 rabbits in each): animals in model group were given normal saline by gavage, animals in positive control group were given aspirin (0.2 g/kg), and animals in Jinhuaqingre groups were given Jinhuaqingre capsules 6.0, 3.0 or 1.5 g/kg, respectively. The changes in body temperature of rabbits were observed. Fifty healthy Kunming mice were divided into 5 groups (10 mice in each): mice in model group were given normal saline by gavage, mice in positive control group were given aspirin (0.2 g/kg), and those in Jinhuaqingre groups were given Jinhuaqingre capsules 6.0, 3.0, 1.5 g/kg, respectively. Matrix coloration method was used to detect the degradation rate of endotoxin in mice. Results: The body temperature in rabbits of high and medium dose Jinhuaqingre capsule groups declined significantly 60 min after drug administration, and the temperature of high-dose group returned to the baseline after 300 min; while the body temperature of low-dose group started to decline at 180 min after drug administration. The endotoxin degradation rates in mice of high, medium and low dose groups was (56.73±3.12)%, (47.23±1.77)% and (21.08±2.30)% at 30 min after drug administration; those were (82.76±1.00)%, (64.75±1.77)% and (38.21±1.57)% at 60 min after drug administration, respectively. Conclusion: Chinese herb medicine Jinhuanigre capsules have anti-pyretic and anti-endotoxin effects, which may provide a new option for the treatment of heat-toxin syndrome.

Photocoagulation in rabbits: Optical coherence tomographic lesion classification, wound healing reaction, and retinal temperatures

The rabbit is the most common animal model to study retinal photocoagulation lesions. We present a classification of retinal lesions from rabbits, that is based on optical coherence tomographic (OCT) findings, temperature data, and OCT-follow-up data over 3 months. Four hundred eighty-six photocoagulation lesions (modified Zeiss Visulas® 532 nm CW laser, lesion diameter 133 µm, exposure duration 200 milliseconds or variable, power variable) were analyzed from six eyes of three chinchilla gray rabbits. During the irradiation of each lesion, we used an optoacoustics-based method to measure the retinal temperature profile. Two hours, 1 week, 1 month, and 3 months after the treatment, we obtained fundus color and OCT (Spectralis®) images of each lesion. We classified the lesions according to their OCT morphology and correlated the findings to ophthalmoscopic and OCT lesion diameters, and temperatures. Besides an undetectable lesion class 0, we discerned subthreshold lesions that were invisible on the fundus but detectable in OCT (classes 1 and 2), very mild lesions that were partly visible on the fundus (class 3), and 3 classes of suprathreshold lesions. OCT greatest linear diameters (GLDs) were larger than ophthalmoscopic lesion diameters, both increased for increasing classes, and GLDs decreased over 3 months within each class. Mean peak end temperatures for 200 milliseconds lesions ranged from 61°C in class 2 to 80°C in class 6. The seven step rabbit lesion classifier is distinct from a previously published human lesion classifier. Threshold lesions are generated at comparable temperatures in rabbits and humans, while more intense lesions are created at lower temperatures in rabbits. The OCT lesion classifier could replace routine histology in some studies, and the presented data may be used to estimate lesion end temperatures from OCT images.

Thermal effects of transcranial near-infrared laser irradiation on rabbit cortex

Transcranial near-infrared laser therapy (TLT) improves stroke outcome in animal models. Adequate laser doses are necessary to exert therapeutic effects. However, applying higher laser energy may cause cortical tissue heating and exacerbate stroke injury. The objective of this study is to examine the thermal effect and safety of transcranial near-infrared laser therapy. Diode laser with a wavelength of 808nm was used to deliver different power densities to the brain cortex of rabbits. Cortical temperature was monitored and measured using a thermal probe during the 2min transcranial laser irradiation. Neuro-pathological changes were examined with histological staining 24h after laser treatment. Transcranial laser irradiation for 2min at cortical power densities of 22.2 and 55.6mW/cm2 with continuous wave (CW) did not increase cortical temperature in rabbits. With the same treatment regime, cortical power density at 111.1mW/cm2 increased brain temperature gradually by 0.5°C over the 2min exposure and returned to baseline values within 1–2min post-irradiation. Separately, histological staining was evaluated after triple laser exposure of 22.2mW/cm2 CW and 111.1mW/cm2 pulse wave (PW) and showed normal neural cell morphology. The present study demonstrated that the TLT powers currently utilized in animal stroke studies do not cause cortical tissue heating and histopathological damage.

LIPOPOLYSACCHARIDES OF RALSTONIA SOLANACEARUM: FATTY ACID COMPOSITION AND BIOLOGICAL ACTIVITY

The study of endotoxic activity indicates the relative non-toxicity (1–1.25 mg/kg) of lipopolysaccharides (LPS) from the majority of studied Ralstonia solanacearum strains comparative to enterobacterial LPS. The exception was LPS R. solanacearum 749, which showed a higher (0.4 mg/ kg) toxicity. The strains of R. solanacearum exhibited division into two groups on the basis of their LPS pyrogenic action. LPS of the first group of strains in the second hour after administration caused decreasing of the temperature in rabbits with a tendency to normalisation and during the third hour, the temperature values reached nearly baseline (R. solanacearum 749, 758, 52, 4). LPS of other strains (R. solanacearum 35, TX1 , TS3 , 7954) led to increasing of the temperature in experimental animals by more than 0.45 °C, wich overcomes the physiological norm of healthy animals. The study of R. solanacearum LPS revealed a high level of heterogenity in quantitative and qualitative fatty acid composition.

Use of human MonoMac6 cells for development of in vitro assay predictive of adjuvant safety in vivo

Subunit vaccines composed of recombinant or purified antigens have a good safety record but are poorly immunogenic and require adjuvants to activate innate immunity and facilitate antigen specific immune response. Of the many adjuvant formulations that are under development, very few are licensed mainly due to concerns about adverse side effects. The goal of our study was to develop in vitro assays that could predict toxicity of adjuvants in vivo. Pro-inflammatory cytokines IL-β, IL-6, TNF-α, and IL-8 were measured in human primary monocytes and the monocytoid cell line, MonoMac 6 (MM6), activated with a panel of TLR agonists or with adjuvants. A 0.5EU/ml dose of Standard for endotoxin (previously shown to provide a margin between pyrogenic and non-pyrogenic substances in rabbits) was used as a comparator to establish a “safety threshold”. FSL-1, Pam3CSK4, flagellin, and R848 TLR agonists but not Alum, MF59, Poly I:C, or MPL adjuvants induced cytokines in MM6 cells above the safety threshold. To confirm the predictive value of the in vitro assays, FSL-1 and flagellin were injected intramuscularly into New Zealand White (NZW) rabbits. Both TLR agonists induced fever within 6–8h post-injection followed 24–48h later by increased C reactive protein (CRP). Importantly, an early peak in plasma prostaglandin E2 (PGE2) levels preceded rise in body temperature. In vitro production of PGE2 in monocytes and MM6 cells was found following treatments with various TLR agonists but not with alum, MF59, MPL, or Poly I:C adjuvants. Together, our studies demonstrated a strong correlation between production of pro-inflammatory cytokines above a “safety threshold” and production of PGE2in vitro and an increase in body temperature in rabbits. The developed human cell based assays could provide an important tool for early screening of new molecular moieties and adjuvant formulations and may assist in selection of safer products.

COMPORTAMENTO DA FREQUÊNCIA CARDÍACA E DA TEMPERATURA CORPÓREA EM COELHOS SUBMETIDOS À PARADA CIRCULATÓRIA CARDÍACA

The technique of total circulatory arrest (TCA), or inflow occlusion , consists in preventing the blood entry into the heart chambers by clamping the vena cava and the cranial and caudal vena azygos. However, changes in physiological parameters of the patient can be triggered with the application of this technique. This technique can be easily used in heart intra-cavity diseases, whose correction takes a few minutes, as in pulmonary stenosis or subaortic stenosis. Because low cost and simple implementation, it may be carried out in private clinics. In this trial, the behavior of heart rate and body temperature of rabbits submitted to two periods of five minutes of TCA, by the use of inflow occlusion technique, was evaluated. A period of blood recirculation between occlusions was performed to verify the potential benefits of this practice on the behavior of heart rate and body temperature of the animals. These parameters were assessed throughout the perioperative period. There were two deaths, both in the recirculation period due to the occurrence of ventricular fibrillation. Nevertheless, with the implementation of the period of blood recirculation, we verified that this technique can be used in intra-cardiac surgery lasting up to 10 minutes. KEYWORDS: Circulatory arrest, inflow occlusion, rabbits.

English

In the present study, we examined the effects of hot red pepper on rabbit’s hepatic tissue. Rabbits were orally ingested 2 g/Kg hot red pepper every day for 10 days. Hot red pepper induced a significant increase in temperature of rabbits after oral ingestion of each dose. Hepatic tissue damage was recorded through examination of the stained paraffin embedded sections. Inflammatory cellular infiltration and hepatocytic vacuolation were marked in rabbits ingested with the hot red pepper. Histochemical studies reveal a decrease in both of carbohydrates and protein contents in the liver. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), cholesterol, triglycerides and glucose were decreased in rabbit due to oral ingestion of hot red pepper. These scientific evidences show that hot red pepper possesses some chemical and pharmacological properties which are capable of inducing liver damage. Therefore, based on the findings of this study, the excessive consumption of red pepper is capable of inducing liver damage and so should be avoided.

Preliminary study of hypothermia induced by intraperitoneal cooling in rabbits after cardiopulmonary resuscitation

Objective To explore the safety and rate of intraperitoneal cooling in rabbits after cardiopulmonary resuscitation(CPR). Method There were two experiments. In the experiment one: 15 healthy adult NewZealand rabbits were divided into five groups as per the various amounts, 30, 40, 60, 80, and 100 mL/kg, of priming volume of 4 ℃ cold balanced salts solution injected into peritoneal cavity of rabbits. After injection of priming cold solution, the tympanic temperature between 33 ℃～ 35 ℃. For the maintenance of this mild hypothermia, a intraperitoneal infusion device(patent number ZL200820201265) was connected to the rabbits. The rabbits were rewarmed by using the same device after 12-hour hypothermia. The biochemical parameters were assayed during the experiment. After the rabbits were sacrificed, the liver, ileocecal junction of intestine and kidneys were removed to fix them in 3 % formalin, and examined by using H.E. staining. In the experiment two, another 12 healthy adult New Zealand rabbits were induced into ventricular fibrillation by alternating electric current and then gave CPR for 2 minutes. After return of spontaneous circulation(ROSC), the priming volume of 4 ℃ cold liquid was infused into peritoneal cavity of rabbits, and then the rabbits were connected to the intraperitoneal cooling device to maintain hypothermia for 12 hours. Matched-pairs t test was used for the comparison of biomarkers before and after intraperitoneal cooling. A two-tailed value of P < 0.05 was considered statistically significant. Results In the experiment one, the tympanic temperature of rabbits with priming volume of 80 mL/kg cold solution was decreased quickly reaching the target temperature in(30±2.00) minutes. During the induction of hypothermia, the intraperitoneal temperature reached the target temperature in less than 10 minutes, and was 1 -2℃ lower than the tympanic temperature during the maintenance of hypothermia. The intraperitoneal cooling did not cause damage in the liver, ileocecal junction of intestine and kidney, and did not alter the biomarkers. In the experiment two, the tympanic temperature of rabbits after ROSC was decreased quickly after intraperitoneal infusion of 80 mL/kg 4 ℃ cold solution, and reached the target temperature in(26.00±6.99) minutes, and the intraperitoneal temperature was lowered to reach the target temperature in less than 10 minutes. This cooling method after CPR didn' t disturbance water-electrolyte and acid-base balance. Conclusions The intraperitoneal cooling can safely and quickly induce hypothermia after CPR in rabbits. Key words: Hypothermia; Peritoneal cavity cooling; Cardiopulmonary resuscitation; Rabbit

Development of an Ex Vivo Assay for Use as a Surrogate Model to Assess the Impact of Endotoxin on Cattle

Current guidelines used by the US Food and Drug Administration to establish a safe level of pyrogens in veterinary parenteral products were derived from work designed for products intended for human use, and there is no consensus on what levels of endotoxin or other pyrogens are safe for domestic animals. The accepted biological measures for endotoxins and other pyrogens have been based on measurement of relatively small changes in body temperature in rabbits rather than an assessment of the inflammation caused by the endotoxins. It is difficult to accurately assess the small changes in body temperature caused by low levels of endotoxin in food-producing animals such as dairy cattle. Thus, the true relevance of guidelines to domestic animals is unknown. Accordingly, a whole-blood assay as a measure of endotoxin-induced inflammation was developed to serve as an in vitro surrogate model for either the rabbit pyrogen test or tests in cattle. Induction of interleukin-6 (IL-6) mRNA occurred at concentrations of lipopolysaccharide that ranged from 1 μg/mL through 1 pg/mL. Because there were still differences in IL-6 induction compared with unstimulated cultures, blood from a second set of animals was treated with lipopolysaccharide concentrations ranging from 1 μg/mL to 1 fg/mL. These results demonstrated that induction of IL-6 occurred somewhere between 100 fg/mL and 1 pg/mL. Because the most sensitive chemical assay can detect endotoxin only at a similar range, the whole-blood assay may be a biological assay that could be used in place of the rabbit pyrogen assay.

Computational model for calculating body-core temperature elevation in rabbits due to whole-body exposure at 2.45 GHz

In the current international guidelines and standards with regard to human exposure to electromagnetic waves, the basic restriction is defined in terms of the whole-body average-specific absorption rate. The rationale for the guidelines is that the characteristic pattern of thermoregulatory response is observed for the whole-body average SAR above a certain level. However, the relationship between energy absorption and temperature elevation was not well quantified. In this study, we improved our thermal computation model for rabbits, which was developed for localized exposure on eye, in order to investigate the body-core temperature elevation due to whole-body exposure at 2.45 GHz. The effect of anesthesia on the body-core temperature elevation was also discussed in comparison with measured results. For the whole-body average SAR of 3.0 W kg−1, the body-core temperature in rabbits elevates with time, without becoming saturated. The administration of anesthesia suppressed body-core temperature elevation, which is attributed to the reduced basal metabolic rate.

Peri-operative body temperatures in isoflurane-anaesthetized rabbits following ketamine–midazolam or ketamine–medetomidine

ObjectiveTo investigate alterations in peri-operative body temperatures and oesophageal-skin temperatures in isoflurane-anaesthetized rabbits following either ketamine–midazolam or ketamine–medetomidine induction of anaesthesia. Animal populationFifty client-owned rabbits, (25 male, 25 female) of different breeds anaesthetized for elective neutering (age range: 3–42 months; mass range: 1.15–4.3 kg). Study designRandomized, blinded clinical study. MethodsPre-anaesthetic rectal temperature was measured. A 24 SWG catheter was placed in a marginal ear vein after local anaesthesia. Ketamine (15 mg kg−1) with medetomidine (0.25 mg kg−1) (group KMT) or with midazolam (3 mg kg−1) (group KMZ) was injected intramuscularly (IM). Following endotracheal intubation anaesthesia was maintained with isoflurane in oxygen. Carprofen (3 mg kg−1) and glucose saline (5 mL kg−1 hour−1) were administered through the intravenous catheter. Room temperature and humidity, skin temperature (from tip of pinna) and oesophageal temperature were measured during anaesthesia. Ovariohysterectomy or castration was performed. Rectal temperature was taken when isoflurane was discontinued (time zero) and 30, 60 and 120 minutes thereafter. Atipamezole (0.5 mg kg−1) was administered IM to rabbits in group KMT at zero plus 30 minutes. Mass, averaged room temperature and duration of anaesthesia data were compared using a two-tailed t-test. Age, averaged room humidity, rectal temperature decrease, oesophageal temperature decrease and oesophageal–skin difference data were compared using a Kruskal–Wallis test. p < 0.05 was considered significant. ResultsThe averaged oesophageal–skin temperature difference was significantly greater in group KMT [median 9.85 °C (range 6.42–13.85 °C)] than in group KMZ [4.38 °C (2.83–10.43 °C)]. Rectal temperature decreased over the anaesthetic period was not significantly different between the two groups; however, oesophageal temperature decrease was significantly less in group KMT [1.1 °C (−0.1–+2.7 °C)] than in group KMZ [1.4 °C (0.6–3.1 °C)]. ConclusionsOesophageal–skin temperature difference is larger in rabbits anaesthetized with ketamine–medetomidine combination than ketamine–midazolam. Clinical relevanceThe oesophageal temperature in rabbits anaesthetized with ketamine–medetomidine and isoflurane decreases significantly less than in animals anaesthetized with ketamine–midazolam and isoflurane, during anaesthesia.

Antipyretic Activity of Rhizome of Drynaria quercifolia. in Rabbit

The antipyretic effect of petroleum ether and ethyl acetate soluble fractions of ethanol extract of the rhizome of Drynaria quercifolia. J. Smith (Polypodiaceae) was investigated. Intraperitoneal administration of boiled milk at a dose of 0.5 mL/kg body weight in albino rabbit leads to pyrexia. Intraperitoneal (i.p.) administration of petroleum ether and ethyl acetate soluble fractions of ethanol extract of the rhizome of D. quercifolia. at a dose of 80 mg/kg body weight were shown to significantly reduce the elevated body temperature of rabbit, which was compared with standard aspirin (market product) and solvent used.

Evaluation of skin temperature change as stress indicator in rabbit through infrared thermography

Stress-induced reactions in animals include behavioural and physiological modifications aiming at coping towards the stressor, such as manipulations. Thermography, that is the detection of infrared radiation emitted by a subject, permits to measure the superficial temperature without any contact with the animal. A thermographic system was employed in order to detect the rabbit skin zones most suitable for temperature monitoring during stress challenges. The trial was assessed over a 2-month period. At the end of fattening period, 12 rabbits were housed in single cages and fed ad libitum a commercial diet.Water was also administered ad libitum. During the trial, environmental temperature and relative humidity (daily average) were 21°C and 52% respectively. Rabbits were first analysed in their own cages (basal condition) and then after placing into a containment box (stress condition) for 15 minutes. Due to the presence of thick hair on the body, only ocular area (globe and periocular skin) and internal ear pavilion were suitable for thermographic measurements. Basal condition, were observed during 30 min. (rate 1 image/min).Stress condition were recorded in 2 images both from ocular and ear areas. As reference, the rectal temperatures of rabbits were recorded during basal and stress conditions. To analyse corticosterone level variations induced by stress, two blood samples were taken the day before the test (basal condition) and immediately after the stress condition. Blood was collected using an insulin syringe and the serum analysed using a specific commercial kit for mouse and rat based on RIA competition method with double antibodies. Thermographic data, divided per shoot areas (eye/ear) were the average obtained on all rabbits during the 5 trials.The temperature value of each subject is the average of all the images in the same experimental conditions. Corticosterone data were analysed by analysis of variance according to a linear model.The average of the temperatures recorded by infrared camera was 35.4°C (basal condition) and 35.1°C (stress condition) for eye and 35.3°C (basal) and 34.8°C (stress) for ear pavillon. Average rectal temperature was 39.2°C and 39.7°C during basal and stress conditions, respectively. The corticosterone levels increased from 17.7 µg/ml (basal) to 85.2 µg/ml after stress challenge.The results of this study show that the thermography is a suitable method for the evaluation of superficial temperature variation in rabbit, according to the applied stressor. The variations related to the physiological changes during the stress reaction are evidenced in the ear pavilion and periocular area, where vasoconstriction occurs. Further researches are running in order to standardise the methodology.

Species specificity and tissue tropism of EPEC and related pathogens

Pathogens that cause attaching and effacing (A/E) lesions in infected host cells, including enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC, respectively), Hafnia alvei and Citrobacter rodantium, exhibit species specificity and tissue tropism[1xDonnenberg, M.S., Kaper, J.B., and Finlay, B.B. Trends Microbiol. 1997; 5: 109–114Abstract | Full Text PDF | PubMed | Scopus (201)See all References[1]. In many cases, these involve specific attachment. In EPEC and related pathogens, intimin is the adhesin that has been implicated in mediating colonization and tissue tropism. Dr Kaper's recent, thoughtful article in Trends Microbiol. on the virulence of EPEC (Ref. [2xKaper, J.B. Trends Microbiol. 1998; 6: 169–172Abstract | Full Text | Full Text PDF | PubMed | Scopus (57)See all References[2]) describes new aspects of EPEC infection; among these is the realization that EPEC and EHEC translocate the intimin receptor (Tir/EspE) into the host cell[3xKenny, B. et al. Cell. 1997; 91: 511–520Abstract | Full Text | Full Text PDF | PubMedSee all References, 4xDeibel, C. et al. Mol. Microbiol. 1998; 28: 463–474Crossref | PubMed | Scopus (142)See all References]. Thus, intimin does not seem to recognize a tissue-specific component but instead recognizes a translocated receptor. Indeed, in their response to Kaper's article, Finlay et al.[5xFinlay, B.B. et al. Trends Microbiol. 1998; 6: 172–173Abstract | Full Text | Full Text PDFSee all References[5]ponder what mechanism is used by EPEC for tissue tropism.Recently, we demonstrated that the EPEC type III secretion system is activated upon contact with epithelial cells[6xWolff, C. et al. Mol. Microbiol. 1998; 28: 143–155Crossref | PubMed | Scopus (170)See all References[6]. This is not surprising, as similar results have been obtained with type III secretion systems of Shigella, Salmonella and Yersinia[7xLee, C.A. Trends Microbiol. 1997; 5: 148–156Abstract | Full Text PDF | PubMed | Scopus (170)See all References[7]. An attractive hypothesis is that the elusive recognition process that triggers type III secretion systems might be a tissue-specific event. This event would dictate where Tir and EspE are translocated and thus dictate the site of colonization. An additional layer of specificity might reside in initial attachment, as contact activation of the type III secretion system and translocation of EspB and Tir are dependent upon attachment to the host cell[6xWolff, C. et al. Mol. Microbiol. 1998; 28: 143–155Crossref | PubMed | Scopus (170)See all References[6]. Currently, intimin is the only EPEC factor known to function as an adhesin in vivo[8xHicks, S. et al. Infect. Immun. 1998; 66: 1570–1578PubMedSee all References[8]. It is possible that the presumably weak and Tir-independent attachment activity of intimin[9xFrankel, G. et al. J. Biol. Chem. 1996; 271: 20359–20364Crossref | PubMed | Scopus (150)See all References[9], or some other adhesin, plays a role in jump-starting an efficient translocation process. Once a small amount of Tir is translocated, EPEC establishes an intimate contact and enters into a phase of enhanced translocation[6xWolff, C. et al. Mol. Microbiol. 1998; 28: 143–155Crossref | PubMed | Scopus (170)See all References[6]. At this stage, Tir-independent attachment activity is no longer needed.A third layer of specificity might reside in the transcriptional regulation of expression of the type III secretion system in response to environmental cues. For example, human-specific EPEC secretes Esps at 37°C but not at 42°C. In contrast, 42°C, which is the body temperature of rabbits, is the optimal temperature for Esp secretion by rabbit-specific EPEC (RDEC-1)[10xAbe, A. et al. Infect. Immun. 1997; 65: 3547–3555PubMedSee all References[10].It remains to be seen whether this hypothesis for EPEC species specificity and tissue tropism will stand up to testing. A critical point is to define, at the molecular level, the events that mediate the contact activation of the type III secretion system of EPEC.

Modulating effect of sodium diethyldithiocarbamate on neutrophils in normal, febrile and cold-stressed rabbits.

The studies were conducted on normal, febrile and cold-stressed rabbits. Fever was induced by a single intravenous injection of 1 micrograms/kg of E. coli lipopolysaccharide (LPS). The animals were submerged in ice-water for 20 s and then were kept at -15 degrees C for approx. 8 min., until their body temperature dropped by 3 degrees C. Sodium diethyldithiocarbamate (DTC) was injected i.v. to normal, febrile and cold-stressed rabbits, in a single dose of 2 or 20 mg/kg. The effect of DTC on body temperature, the number of neutrophils in blood, phagocytic activity of neutrophils and their ability to reduce nitroblue tetrazolium (NBT) were evaluated. It was found that DTC administered in a dose of 2 or 20 mg/kg did not affect the body temperature of rabbits. In normal rabbits, DTC did not change the number of neutrophils, but increased their phagocytic activity and ability to reduce NBT. In febrile rabbits, DTC depending on the dose, shortened the stimulating effect of LPS on neutrophil ability to reduce NBT but enhanced and prolonged the effect of pyrogen on neutrophil phagocytic activity. The rabbits treated with DTC prior to hypothermia exhibited shorter neutrophilia resulting from cold stress. In addition, DTC administered to the rabbits before their exposure to cold stress proved to be a partial or even total protection against the decrease in NBT reducing ability and phagocytic activity of blood neutrophils.