Pharmacokinetics of carprofen and firocoxib for medication control in racing greyhounds.

Animals used in sport should be treated as required to ensure animal welfare but any such use of medication should also be controlled to ensure integrity. Pharmacokinetic studies on groups of six greyhounds were performed to measure plasma and urine levels of carprofen and firocoxib to inform medication control advice. Using the standard methodology for medication control the Irrelevant Plasma Concentration was determined as 20 and 2 ng/mL for carprofen and firocoxib, respectively. The Irrelevant Urine Concentration was also determined as 0.3 and 2 ng/mL for carprofen and firocoxib, respectively. These Irrelevant Plasma and Urine Concentrations will allow laboratory Screening Limits, Detection Times and Withdrawal Time advice to be determined and publicised by regulators of greyhound racing. The Screening Limits will also inform Recommended Limits of Detection if meat-containing residues of these medications are fed to greyhounds.

Different steric characteristics of beta 1- and beta 2-adrenoceptors.

beta-Adrenoceptors of lung (75% beta 2) and heart (95% beta 1) of calf were labelled with 3H-(-)-propranolol. The stereoisomers of 10 ligands were used to inhibit the binding of 3H-(-)-propranolol to membrane particles. The affinity ratio of stereoisomers is consistently greater for beta 1-adrenoceptors than for beta 2-adrenoceptors, regardless of whether the ligands are agonists, partial agonists or antagonists. The beta 1-adrenoceptor appears to possess stricter steric requirements than the beta 2-adrenoceptor. This property may prove helpful in differentiating the beta-adrenoceptor subtypes during receptor solubilization and purification.

High affinity of carozolol for beta-adrenoceptors coupled to the adenylyl cyclase in ventricular myocardium of kitten and Xenopus laevis.

Catecholamine-induced stimulation of adenylyl cyclase in ventricular membranes of kitten and Xenopus laevis was antagonized competitively by carazolol. Apparent equilibrium constants ranging between 100-170 pM were estimated for the beta-adrenoceptor-carazolol complex.

An initial characterization of human heart beta-adrenoceptors and their mediation of the positive inotropic effects of catecholamines.

The positive inotropic effects of catecholamines were studied on samples of ventricular myocardium taken from patients undergoing open heart surgery. The adenylyl cyclase and binding of 3H-(-)-bupranolol were examined in membrane particles prepared from similarly obtained samples. The equilibrium dissociation constant (KD) for (-)-bupranolol was estimated in 4 ways: blockade of the positive inotropic effects of catecholamines, blockade of the stimulation of the adenylyl cyclase by catecholamines, saturation binding of 3H-(-)-bupranolol, inhibition of the binding of 3H-(-)-bupranolol by its unlabeled stereoisomers. The estimates of KD fall in the range 0.5-1.4 nmol/l. The stereo-selectivity ratio (KD (+)-isomer/KD (-)-isomer) is 73. Both values for bupranolol are very similar in cat and man. The inotropic potency of (-)-noradrenaline is nearly 2 orders of magnitude higher in cat heart tissues than in tissues from human hearts. The difference in inotropic potencies between species is only partially accounted for by the five-fold lower potency of (-)-noradrenaline for the human heart adenylyl cyclase as compared to the cat enzyme.

Rapid, single-step isolation of equine neutrophils on a discontinuous Percoll density gradient.

A rapid single-step procedure for isolation of equine neutrophils (PMNS) from peripheral blood is described. A discontinuous gradient of two Percoll solutions (densities of 1.087 kg litre-1 and 1.108 kg litre-1 was used. The PMNS were isolated to more than 95 per cent purity with a viability of more than 99 per cent and a cell recovery of more than 83 per cent. The method used was rapid and reproducible and the equipment required is relatively simple. The function of the recovered cells was assessed in a chemotactic assay using a modified Boyden chamber technique.

Antibiotic therapeutics in laboratory animals.

Information on antibiotic therapeutics in laboratory species, especially in rodents and rabbits, is reviewed. A number of areas are considered: interference by antibiotics with an experiment, antibiotic toxicity, routes of administration, effects of formulation on bioavailability, antibiotic prophylaxis, use of combinations of antibiotics, misuse of antibiotics, regulatory approval for antibiotic use in animals, sources of information on antibiotic indications and dose, and extrapolation of dose information from other species.

Illustrated guide to surgical technique for vasectomy of the common marmoset.

The surgical technique for vasectomy of the common marmoset (Callithrix jacchus) is described and illustrated.

Diarrhoea and increased intestinal permeability in laboratory beagles associated with proximal small intestinal bacterial overgrowth.

Repeated episodes of diarrhoea were seen in 4 laboratory beagles after experimental renal surgery and feeding a modified diet. Small intestinal bacterial overgrowth (SIBO) was suspected by exclusion of other causes and measurement of plasma folate. SIBO was confirmed by quantitative duodenal bacteriology. Beagles with SIBO can show no clinical signs, experimental stress and dietary change may have been reasons why these 4 beagles exhibited clinical signs with SIBO. Despite normal gut histology an increase in gut permeability was found using sugar absorption tests. This increased permeability had the potential to cause variations in drug absorption during experimental studies.

An investigation into the effects of solid or grid cage flooring on the welfare of laboratory rats.

The welfare of laboratory rats housed on either solid or grid floors was investigated in several ways. No differences were found in body weight gain, food consumption or water consumption amongst rats housed in either condition. When handling was standardized between the 2 groups, there was no correlation between flooring and docility. Preference testing revealed that rats chose to dwell on solid floors rather than grids, regardless of previous housing experience. This preference for solid floors was particularly marked (88%) when the animals were resting and much less marked during activity (55.4%). Since the rats were observed to spend 70 to 75% of their time resting, it was concluded that their welfare was likely to be improved by housing them on solid floors.

The use of a novel operant test to determine the strength of preference for flooring in laboratory rats.

A previous study showed that laboratory rats preferred to dwell on a solid floor rather than a grid one, particularly when resting (Manser et al. 1995). The strengths of this preference was investigated in an operant trial using a novel test apparatus, which consisted of a grid-floored cage and a solid-floored cage, joined via a central box containing a barrier whose weight was adjustable. Trials in which rats had to lift the barrier in order to explore the whole apparatus were alternated with those in which the rats were confined on the grid floor and then had to lift the barrier in order to reach the solid floor. The latter trials were carried out at the beginning of the light period when the rats were seeking a resting place. In both trials, the weight of the barrier was progressively increased for each rat, until a maximum weight was found which it would lift either to explore its environment (weight A) or to reach the solid floor (weight B). No significant differences were found between weights A and B, showing that rats would work as hard to reach a solid floor to rest on as they would to explore a novel environment. The apparatus used could with some modifications, be appropriate for use in other operant studies in laboratory rats.

Investigations into the preferences of laboratory rats for nest-boxes and nesting materials.

Nest-boxes and nesting materials were considered potentially useful items with which to enhance the environment of rats housed in standard laboratory cages. This study was carried out to determine whether such items are actually used by rats, and if so, what features are important in their design. Laboratory rats were allowed to choose between four commercially available nest-boxes. Nest-boxes were preferred to other parts of the cage but the nest-box most frequently selected was not suitable for routine laboratory use. Accordingly a new nest-box was designed, incorporating features apparently attractive to the animals. This was a simple structure of opaque perspex, consisting of a roof and three walls. Similarly, rats were exposed to six commercially available nesting materials and those consisting of long paper strips were most preferred.

Operant studies to determine the strength of preference in laboratory rats for nest-boxes and nesting materials.

Previous work has shown that laboratory rats preferred to use nest-boxes and nesting materials rather than empty parts of the cage. In preference tests, they chose opaque or semi-opaque nest-boxes and long strips of soft paper nesting material. Choice tests to demonstrate a preference between nest-boxes and nesting material were not possible because nesting materials were carried into the nest-boxes. Furthermore, preference tests did not show how important these items were to the animals. Accordingly, operant tests were conducted, in which the rats had to lift a weighted door in order to gain access to an empty cage, or one containing a nest-box, nesting material or both items. By progressively increasing the weight of the door in subsequent trials, it was shown that the rats would carry out more work to reach a nest-box, with or without nesting material, than to reach an empty cage.

Bacterial counts in canine duodenal fluid after exposure to saline, sodium bicarbonate and hypertonic dextrose solutions used to maintain patency of chronically implanted catheters.

Flushing of intestinal vascular access ports (VAPs) is commonly performed to prevent the problems of blockage and infection, and in this study four different flushing solutions were compared. The growth of bacteria from canine duodenal contents was compared in: 0.9% saline, 50% dextrose, 8.4% sodium bicarbonate (NaHCO3) and 0.01 M phosphate buffered saline (PBS). Duodenal contents from three laboratory beagles were serially diluted in these four solutions, spread plated onto agar at 24 h periods for 7 days and bacterial counts were performed. Immediately after the duodenal juices were added, no significant differences could be seen in bacterial counts with any of the solutions. Over the 7 day period, bacterial numbers greatly increased in saline and phosphate buffered saline, but greatly decreased in dextrose and sodium bicarbonate solutions. Dextrose and sodium bicarbonate appeared to be the most promising flushing solutions tested to minimize infections of associated intestinal VAPs.

An illustrated guide to endotracheal intubation in small non-human primates.

Endotracheal intubation allows precise delivery of inhaled anaesthetic agents. Intubation in small non-human primates (less than 1 kg), is straightforward, using commercially available equipment, and careful positioning of the animal. Equipment and methods are fully described and illustrated.