C. J. Green

Ketamine alone and combined with diazepam or xylazine in laboratory animals: a 10 year experience.

Ketamine alone or supplemented by diazepam or xylazine has been used and evaluated as an anaesthetic in a range of animals including snakes, tortoises, lizards, birds, ferrets, dogs, cats, pigs, sheep, goats, non-human primates, rabbits, guineapigs, rats, mice and hamsters. Ketamine alone has severe limitations in most species, but in combination has proved valuable.

Rabbit renal autografts as an organ preservation model

Surgical details are given of a reliable and simple technique for autografting rabbit kidneys which have been preserved by different methods. In a trial series of 20 autografts, 16 rabbits, supported by 1 grafted kidney alone, survived beyond 4 months and were then killed and autopsied. The results are compared with trials using other operative techniques.

Anaesthetic gases and health risks to laboratory personnel: a review

The evidence that chronic exposure to inhalational anaesthetic agents may be associated with psychomotor, hepatic and renal dysfunction, to increased susceptibility to infections and neoplastic disease, and to an increased incidence of miscarriages and foetal abnormalities, is discussed. The risk to pregnant women seems greatest after exposure to rather high concentrations of nitrous oxide. Although it is not suggested that all laboratory premises will be equally at risk, such levels as 400 ppm halothane and 8000 ppm nitrous oxide can build up in small poorly-ventilated rooms when these agents are used for several hours at a time. A strong plea is entered for all to be aware of the hazard and to ensure that good ventilation and preferably, purpose-built scavenging equipment are installed wherever inhalational agents are used.

Metomidate, etomidate and fentanyl as injectable anaesthetic agents in mice

Light surgical anaesthesia lasting 12-15 min was produced by metomidate at 50 mg/kg and by etomidate at 30 mg/kg after intraperitoneal injection. Full surgical anaesthesia lasting about 160 min was achieved after subcutaneous injection of a metomidate-fentanyl mixture (60 mg/kg:0·06 mg/kg) and this proved superior to etomidate-fentanyl given subcutaneously or intraperitoneally. It was concluded that metomidate-fentanyl is superior to pentobarbitone and tribromoethanol as an injectable anaesthetic for mice.

Successful anaesthesia and small-bowel anastomosis in the guineapig

Using methoxyflurane and paying critical attention to maintenance of body temperature, tracheal aspiration and fluid replacement, guineapigs were rendered suitable for intraperitoneal operations lasting up to 3 h. Anaesthetic mortality was less than 2%. A technique of small-bowel anastomosis was developed using interrupted soluble sutures meticulously placed 1 mm apart and taking bites 1 mm deep. Survival was 95%.

Microsurgery in the clinic and laboratory

Laboratory animals have been crucial to the development of modern microsurgical techniques which are now routinely used in many clinical departments worldwide. In return, microsurgical techniques are important in biomedical research as they allow many surgical procedures to be performed on rodents instead of dogs, pigs or primates. This has obvious advantages in terms of low cost, the use of statistically valid numbers for comparison and the availability of genetically defined animals which are more likely to give valid answers to immunological questions. Microsurgical reconstruction is important in plastic, orthopaedic, urogenital, vascular and peripheral nerve surgery in man and it is likely that it will become part of every surgeons training in the near future. In this review, the instrumentation essential to any microsurgical enterprise and the sutures available are described. Basic microsurgical techniques for end-to-end and end-to-side anastomosis of small vessels and for joining peripheral nerves, oviducts and other tubular structures are given in outline. Techniques for transplanting kidney, heart, heart and lung, liver, spleen, pancreas, small bowel, stomach, testicle, ovary and whole joint are only outlined but key references are given. Finally, some of the clinical indications for microsurgical reconstruction are reviewed.

The sedative effects of climazolam and climazolam with fentanyl–fluanisone in rats (Rattus norvegicus)

A trial of the sedative effects of a novel benzodiazepine, climazolam, and of a mixture of climazolam and fentanyl–fluanisone was undertaken in male and female Sprague Dawley and Lewis strain rats (Rattus norvegicus) of different ages. At the recommended intravenous therapeutic dosage of 0·25 mg/kg, climazolam sedated the rats but failed to inhibit the righting reflex or responses to painful stimuli. Even at 25 times the recommended dosage, there was no anaesthetic effect. Predictable and satisfactory surgical anaesthesia was not obtained with the mixture of climazolam and fentanyl–fluanisone administered intraperitoneally. In contrast with diazepam and midazolam, climazolam failed to potentiate the sedative analgesic properties of fentanyl–fluanisone: indeed many animals retained their tail and pedal pinch reflexes. The results also revealed significant differences in effect related to strain and age but not to sex.

Amyloidosis as an incidental finding in rats on experiment

In a review paper (Dunn, 1967) on amyloidosis in laboratory animals, covering both the spontaneous and experimentally-produced disease, it was stated that rats seldom suffer from spontaneous amyloidosis, and that attempts to produce the condition had failed. This is puzzling, as it is commonly seen in mice and is not infrequently found in guinea-pigs, rabbits and hamsters. There is no reason to suppose that rats are any less susceptible to chronic inflammatory processes than other laboratory species. It was therefore of considerable interest when amyloid was encountered in rats which had been used for simple radiographic studies. Deposits were found in all organs which were examined histologically; they were strongly stained with congo-red and exhibited bright green birefringence when examined with polarised light. Confirmation by electron microscopy was not attempted. The animals were from a conventional Sprague-Dawley rat colony known to suffer from chronic respiratory disease with characteristic lesions in the lung. Both Mycoplasma pulmonis and Bordatella bronchiseptica were recovered from the upper respiratory tract and lungs, whilst significant antibody levels to Sendai virus were consistently demonstrated in individual serum samples. The radiographic study (Kreel, Green & Tavill, 1972) entailed immobilising rats by intramuscular injection of 0·05 mljlOO g bodyweight fentanyl-haloanisone (Hypnorm; Crown Chemicals Ltd, Lamberhurst, Kent) followed by intravenous injection via the penile vein of 1·2 ml of radio-contrast medium (Urovision, a mixture of sodium amidotrizoate and meglumine amidotrizoate; Schering A.G., Berlin). Several angiograms and a pyelogram were taken. This was repeated over a period of 6 days.

A chelator is required for microsomal lipid peroxidation following reductive ferritin-iron mobilisation

In the past, antioxidant and chelator studies have implicated a role for iron-dependent oxidative damage in tissues subjected to ischaemia followed by reperfusion. As ferritin is a major source of iron in non-muscular organs and therefore a potential source of the iron required for oxygen radical chemistry, we have determined conditions under which ferritin iron reduction leads to the formation of a pool of iron which is capable of catalysing lipid peroxidation. Under anaerobic conditions and in the presence of rat liver microsomes, flavin mononucleotide (FMN) catalysed the reduction of ferritin iron as shown by both continuous spectrophotometric measurements of tris ferrozine-Fe(II) complex formation and post-reaction Fe(II) determination. The presence of either ferrozine or citrate was not found to alter the time course or extent of ferritin reduction. In contrast, the addition of air to the reactants after a 20 min period of anaerobic reduction resulted in peroxidation of the microsome suspension (as determined with the 2-thiobarbituric acid test) only in the presence of a chelator such as citrate, ADP or nitrilotriacetic acid. These results support the concept that reduced ferritin iron can mediate oxidative damage during reperfusion of previously ischaemic tissues, provided that chelating agents such as citrate or ADP are present.

LACTOBACILLUS SP. ISOLATES FROM MOUSE LIVERS: SAPROPHYTE OR POTENTIAL PATHOGEN?

Over a 3-year sampling period Lactobacillus sp. has been isolated from the livers of barrier-maintained and conventional mice. Serology has failed to detect presence of mouse hepatitis virus antibodies in any of these mice. Histopathological examination revealed only mild fatty change and small monocytic infiltrates.