2011 - Volume 38 - Issue 2

81-87
Anesthesia for Intraocular Surgery in Rabbits
by Sarbani Hazra, Himagshu Palui Bhabatosh Biswas & Aditya Konar

The purpose of the study was to assess a ketamine/xylazine combination along with retrobulbar block using 4% lignocaine HCl for performing intraocular surgery in rabbits. To do so ten healthy adult New Zealand White rabbits aged 1.5-2 years of either sex weighing 2-3 kgs were selected for unilateral cataract extraction by phacoemulsification . Xylazine HCl was used as preanesthetic at a dose rate of 5 mg/kg, i.m., followed by Ketamine HCl at a dose rate of 35mg/kg, i.m. A retro bulbar block was performed with 4% lignocaine HCL. The anesthetic depth was judged by ear pinching reflex. The time for onset and duration of anesthesia was found to be 7±0.5 minutes and 35.5±1.2 minutes respectively. A central eyeball fixation following retro bulbar block was obtained in all the cases. The mean values recorded before induction of anesthesia and during anesthesia of rectal temperature (38.090C±0.2 vs. 37.290C±0.2), heart rate in beats per minute (276±1.2 vs.272±1.1), arterial blood pH (7.35±0.02 vs. 7.32±0.02), bicarbonate (16.2±1.2 vs. 20.3±1.8), PaCo2 (26.09±2.3 vs. 27.52±2.3) and PaO2 (84.79±1.9 vs. 80.39±1.1) did not vary significantly (P>0.05). Recovery was smooth and complete in 32.5±2.8 minutes. Conclusion: the anesthetic regimen provides adequate condition for conducting intraocular surgery in rabbits.

91-96
Pneumocystis Murina Infection in Immunodeficient Mice in a Closed Barrier Unit: a Case Report
by Frederik Dagnæs-Hansen & Knud Poulsen

Pneumocystis is an important pathogen in immunocompromised individuals. In colonies of immunodeficient mice, P. murina can cause wasting disease and make the breeding and maintenance of immunodeficient animals difficult, unless they are continuously treated with sulfadiazin/trimethoprim. At University of Aarhus immunodeficient and immunocompetent mice were co-housed in a barrier unit. The facility was closed for entrance of animals (except for embryos for embryo transfer) and the entrance for personnel was highly restricted. The breeding performance of immunodeficient animals was comparable to that of the immunocompetent mice for a period of more than 3 years, until wasting disease and decreased litter size specifically in the breeding colony of immunodeficient mice occurred. Clinical symptoms of affected mice included laboured breathing, hunched up position, unwillingness to move, and ruffled coat. Pneumocystis infection was confirmed by histological examination and PCR. The partial sequence of the mitochondrial large subunit rRNA gene obtained (GenBank accession no AF548626) displayed 99 % identity to that of Pneumocystis murina (formerly Pneumocystis carinii f.sp.muris) found in laboratory mice. The immunodeficient animals were removed from the barrier and treated 
with sulfadiazin/trimethoprim in a separate unit. After the removal of immunodeficient animals, Pneumocystis could not be detected by PCR in the remaining animals. Our data add to the growing evidence that immunocompetent animals harboring Pneumocystis as a subclinical infection may be reservoirs for this organism. Still it remains to be determined how the infection was introduced and whether a latent infection can persist or the outbreak was caused by leakage in the barrier.

99-107
Comparative Pharmacokinetics of Orbifloxacin Following a Single Intravenous or Oral Administration to Healthy and Diabetic Rats
by Elias Gebru, Zhi-Qiang Chang, Henrique Cheng, Joong-Su Lee, Jong-Choon Kim and Seung-Chun Park

The single-dose disposition kinetics of orbifloxacin was determined in clinically healthy and diabetic rats after intravenous or oral administration of 5 mg/kg body weight. Orbifloxacin concentrations were determined by HPLC with fluorescence detection. The HPLC method was sensitive, specific and repeatable. A systemic bioavailability of 99.1% and 108 %, and a Cmax of 6.55 ± 1.09 μg /mL and 8.63 ± 1.09 μg /mL were observed in healthy and diabetic rats, respectively. The terminal half-life after intravenous and oral administration was 4.17 ± 0.38 h and 4.03 ± 0.41 h for healthy and 2.31 ± 0.34 h and 3.03 ± 0.28 h for diabetic rats. Orbifloxacin was cleared more rapidly in diabetic rats (0.15 ± 0.01 L/kg.h) than healthy group (0.11 ± 0.01 L/kg.h), with longer mean resident time (MRT) values observed in the latter. Other kinetic parameters were almost the same between the healthy and diabetic groups. This investigation revealed that a dose of 5 mg/kg orbifloxacin can be safely and effectively used to combat infections in rats of either group associated with susceptible bacteria.

111-115
A Low Cost Face Mask for Inhalation Anaesthesia in Rats
by Balafas E, Papastefanou A, Katsimpoulas M & Kostomitsopoulos N

Inhalation anaesthesia in small laboratory rodents has become very popular in Biomedical Research. A common method to deliver volatile anesthetic agents is through a face mask. The main disadvantage of this method is the exposure of personnel to anaesthetic agents. The authors describe a low-cost face mask, made with materials commonly accessible in the operating room that can be connected to an anaesthetic machine eliminating personnel exposure to hazardous levels of anaesthetic agents and allowing for effective adjustments to the anaesthetic depth.

117-127
Protocol of Insulin Therapy For Streptozotocin-Diabetic Rats Based on a Study of Food Ingestion and Glycemic Variation
by Liliane Sena Pinheiro, Anderson Dutra de Melo, Ana Eliza Andreazzi, Luiz Carlos de Caires Júnior, Mônica Barros Costa & Raúl Marcel González Garcia

Aim: An extensive volume of scientific work uses diabetic rats treated with insulin, but the protocols of treatment are poorly described. The purpose of this study was to analyze the glycemia and food intake behavior to establish the protocol of insulin treatment for these diabetic rats. The efficiency of our methodology was tested by evaluating the biochemical profile of the animals. Methods and results: We used male Wistar rats with diabetes mellitus (DM) induced by streptozotocin. We analyzed the food intake and glycemic level variations hourly throughout 24h to determine the schedules and doses of insulin to be administered. Following this, we tested the efficiency of different doses and fractionation of NPH insulin in keeping the glycemic levels close to normoglycemia. The best daily dose of insulin was 5 U/day, 1 U being applied at 13h and the remaining 4 U at 19h. The efficacy of the insulin therapy was evaluated by comparing body weight and biochemistry parameters among the experimental groups, as well as glycemia measurement. Glycemic levels, total cholesterol, c-LDL and c-VLDL were reestablished in diabetic rats treated with insulin (ITD). DM did not change the levels of c-HDL, triglycerides and fructosamine. Body weight gain was similar between control and ITD rats. Conclusion: We established an insulin therapy that consists of a daily insulin dose for all animals to maintain most of them at or near normoglycemia. Our results provide, what is to our knowledge, the most detailed schedule of insulin therapy for treating STZ-diabetic rats.