Effects of early atipamezole reversal of medetomidine-ketamine anesthesia in mice.

Rodents are often anesthetized by using ketamine and medetomidine, with reversal by atipamezole. Methods vary for times of administration of the atipamezole, and literature is lacking regarding appropriate reversal time. We investigated the recovery of mice reversed with atipamezole 10 min (early) or 40 min (late) after induction of anesthesia. Time to regain pinch-reflex or righting reflex did not differ between the 2 reversal points, but time to walking was significantly greater in mice that underwent early reversal with atipamezole. This delay was not mitigated by administration of atropine as part of the anesthetic regimen. Inclusion of acetylpromazine in the anesthetic regimen shortened the time needed to reach a surgical plane of anesthesia but also prolonged recovery times as determined by righting reflex and time to walking.

Serial exhaled nitric oxide measurements in the assessment of laboratory animal allergy.

BACKGROUND: Laboratory animal allergy (LAA) may cause eosinophilic airway inflammation, for which exhaled nitric oxide (FE(NO)) measurements are sensitive and specific. Our objective was to assess whether serial FE(NO) measurements might detect exposure-related inflammation in laboratory animal workers. METHODS. Fifty laboratory animal workers participated. Measurements of FE(NO) and spirometry were obtained at baseline (Friday) and twice-daily following a weekend with no animal contact. RESULTS: Eleven of 50 subjects had work-related symptoms, and 2 of 11 had positive serology for LAA. Baseline FE(NO) was high (> 150 ppb) in the two seropositive subjects and increased progressively during the working week in one subject, confirming exposure-driven airway inflammation. In seronegative subjects, mean FE(NO) levels were 19.8 (standard deviation [SD], 20.1) and 21.7 (SD, 20.8) in the symptomatic and nonsymptomatic groups, respectively, with no significant changes in FE(NO) over time. CONCLUSION: Serial FE(NO) measurements may provide complementary information in the assessment of possible occupational sensitisation. The sensitivity and specificity of this approach to diagnosing occupational asthma requires further evaluation.

The effect of warm humidified CO2 on the dissipation of residual gas following laparoscopy in piglets.

STUDY OBJECTIVE: To determine whether residual gas volume reduces more quickly after insufflation with humidified CO(2) compared with dry CO(2). DESIGN: Animal study (Canadian Task Force classification I). SETTING: University. INTERVENTION: Piglets were randomly divided into two groups of five and underwent abdominal insufflation with either cold, dry CO(2) or warm, humidified CO(2). MEASUREMENTS AND MAIN RESULTS: Following insufflation, anteroposterior and lateral gas-bubble radiographic images were obtained at 5, 15, 30, 45, and 60 minutes, and the area of each gas-bubble profile calculated. Blood samples were obtained at 0, 2, 4, and 5 hours, and they were analyzed for IL-1beta and TNFalpha. Peritoneal tissue samples were obtained on euthanasia at 5 hours for histological analysis. The results indicate that following pneumoperitoneum, residual CO(2) dissipates more rapidly when the gas is heated and humidified compared with when it is cool and dry. This is associated with a reduction in the duration of the inflammatory response as measured by TNF alpha production, although no histologic differences in the peritoneal tissue were observed. CONCLUSION: Heating and humidifying CO(2) leads to faster dissipation of residual gas associated with a reduced duration of inflammation, which may contribute toward a reduction in postlaparoscopic pain.

Decrease in hepatic drug-metabolizing enzyme activities after removal of rats from pine bedding.

Wood is often used as a contact bedding material for laboratory animals. It has been established that wood, particularly softwood, has the potential to induce hepatic drug-metabolizing enzymes. However, to the authors' knowledge, changes in enzyme activity after removal of animals from bedding have not been characterized. The purpose of the study reported here was to determine how hepatic ethoxyresorufin-O-deethylation and p-nitrophenol hydroxylation activities alter over time after removal of rats from pine bedding. Male rats, three to four months old, raised in cages containing pine bedding, were transferred to wire-bottomed cages. At various times thereafter (up to 84 days), groups of rats were euthanized and the liver was processed to obtain microsomes. The microsomal protein and total cytochrome P450 (CYP) content and enzyme activities were determined. Significant differences in total microsomal protein or total CYP values were not observed over the 84 days, but a decrease in ethoxyresorufin-O-deethylation and p-nitrophenol hydroxylation activities was detected. For p-nitrophenol hydroxylation, the decrease was exponential, with a half-life of approximately nine days, whereas for ethoxyresorufin-O-deethylation, a rapid decrease in activity in the first week was followed by a reduced rate of decrease thereafter. Enzyme activities did not stabilize for at least six weeks. Researchers using laboratory animals should, therefore, be aware that it takes several weeks for enzyme activities to stabilize once animals are removed from the bedding.

Evaluation of radiography, ultrasonography and endoscopy for detection of shell lesions in live abalone Haliotis iris (Mollusca: Gastropoda).

Radiography, ultrasonography and endoscopy were examined for their efficacy as non-destructive techniques for the detection of shell lesions in the marine gastropod Haliotis iris Gmelin. X-rays provided 69% correct diagnoses, with detection being restricted to those lesions which were mineralised. Ultrasound also showed potential to reliably detect lesions (83% correct diagnoses), but only where the lesions demonstrated a clear 3-dimensional relief. Lesion dimensions were underestimated using ultrasound. Endoscopy, applied to anaesthetised individuals, provided the most accurate method (92% correct diagnoses) for lesion detection and, although invasive, had no discernible effect on survival of the abalone 8 mo after screening.