Identification by 16S rDNA fragment amplification and determination of genetic diversity by random amplified polymorphic DNA analysis of Pasteurella pneumotropica isolated from laboratory rodents.

Pasteurella pneumotropica is an opportunistic bacterium frequently isolated from colonies of various laboratory rodents. Identification of this species, including its differentiation into two distinct biotypes (Jawetz and Heyl), is usually based on the use of conventional bacteriologic methods. In this study, a 16S rDNA fragment amplification procedure was developed for use as an alternative method for identification and differentiation of P. pneumotropica. Polymerase chain reaction (PCR) products were two distinctive fragments of 937 and 564 bp specific for biotypes Jawetz and Heyl, respectively. Specificity of PCR products could be achieved by EcoRI cleavage, leading to 596 plus 341-bp and 346 plus 218-bp fragments for each of the amplification products. Use of this procedure confirmed identification of 34 field isolates and allowed definitive identification of some strains that could not have been done by use of bacteriologic examinations. Field isolates subjected to random amplified polymorphic DNA (RAPD) analysis had high genetic diversity among biotype Jawetz strains in contrast to biotype Heyl strains. In conclusion, RAPD could represent an additional means for identification of ambiguous strains of biotype Heyl and a valuable epidemiologic tool for identification of biotype Jawetz strains of P. pneumotropica.

Early (1 to 24h) plasma atrial natriuretic factor changes in the rat during antiorthostatic hypokinetic suspension.

Antiorthostatic hypokinetic suspension (AOH) in rat is currently used as an animal model for simulating weightlessness. This maneuver is responsible for a diuresis, a natriuresis and an increase in central venous pressure (CVP). Knowing the role of CVP in atrial natriuretic factor (ANF) secretion, the aim of the study was to examine the early plasma ANF changes during AOH (angle 30-35 degrees) using Morey's model (tail suspension). The rats were divided into 4 groups: 24 population cage (PC), 24 isolated in separate cages (I), 24 were attached by the tail (Morey's model) and remained in the horizontal position (attached horizontal: AH). At the end of this period of 7 d, 12 AH were suspended for 1, 2, 6 and 24 h (AOH) and sacrificed with the controls for plasma ANF determination. Our results show that the level of ANF is significantly (p less than .05) higher in AOH rats after 2 h of suspension (16.6 +/- 2 pg/ml vs 10.9 +/- 1.5). A significant increase is also observed between AOH and AH after 2h of suspension (p less than 0.05). Six hours after suspension ANF presents a sharp decline in AOH and no difference is observed between AOH and AH and I. Morey's tail suspension model seems to be valid for the study of the early hormonal effects of simulated weightlessness for ANF.

Dietary induced changes in catecholamine metabolites in rat urine.

The influence of dietary conditions on the excretion of catecholamine metabolites has been investigated in rats. Four groups of rats were nourished over several days, with the usual cereal rat chow (A) or a synthetic complete food (B) or 15% milk (C) or 12% sucrose solution (D). Interference from cereal-rich diet was observed on most metabolites: dopamine (DA), 3-O-methyldopamine (3-MT), 3,4-dihydroxyphenylacetic acid (DOPAC), norepinephrine (NE) and epinephrine (E). The cereal-induced interference was the highest for conjugated DA metabolites. Sucrose diet suppressed the chemical dietary interferences on DA metabolites but induced sympathetic hyperactivity, together with sustained changes in lipid metabolism, as previously observed in sucrose overfeeding. Milk diet induced too catecholamine release but did not reduce dietary interference on DA and 3-MT. From these results, we conclude that the synthetic cereal-free meal B is convenient in studies including most catecholamine metabolites, except for conjugated DOPAC. In the latter case, sucrose diet proofs more appropriate, provided it is used over a short period.

Principles of ethics in animal experimentation.

The attached principles were compiled at Talloires by the ad hoc international group formed as a result of the International Symposium on 'The Laboratory Animal in the Service of Mankind' held in Lyon (France) in September 1978 in honor of Claude BERNARD on the 100th anniversary of his death. These are in effect a reaffirmation of principles long in practice in many countries. An effort has been made to bring these together in a manner which would be most clearly understood and accepted on an international basis.