Experimental cryptococcosis in guinea pigs

A guinea pig model was used to evaluate immune response to Cryptococcus neoformans. This model shared characteristics with cryptococcosis in humans. Twenty five guinea pigs injected intraperitoneally with 10(7) viable C. neoformans cells developed disseminated disease. Forty days after infection all guinea pigs were killed and autopsy performed. C. neoformans growth in the lungs, brains, livers and spleen of the infected animals were determined. Furthermore, the immune response was characterized by moderate degree of delayed-type hypersensitivity and humoral response. In some organs was observed neutrophil and lymphocyte infiltration with presence of cryptococci cells. The infiltration observed in the organs was probably a consequence of an immune reaction.     

Effects of guinea pig vasoactive intestinal peptide on the isolated perfused guinea pig heart

The pharmacological effects of guinea pig vasoactive intestinal peptide (VIP) were studied in isolated perfused guinea pig hearts. Bolus injections of VIP produced a dose-dependent tachycardia that was not affected by atenolol. A decrease in amplitude of ventricular contractions occurred in response to all doses of VIP. This response was preceded by a small increase in amplitude in 3 of 6 hearts at the highest dose. VIP produced a decrease in perfusion pressure which was prominent after coronary tone was elevated with [Arg8]-vasopressin. The present findings support speculation that VIP may have a role in the regulation of heart rate and coronary blood flow.     

Interstitial pneumonia in guinea pigs

Interstitial pneumonia was observed in 12 male guinea pigs. Grossly, the lung showed clear white areas in the parenchyma. Histological changes in the lung consisted of interstitial pneumonia and formation of granulomas accompanied by bacterial clumps. It was thought that this disorder might have occurred as a bacterial infection.     

Normal electrocardiogram in guinea pig

For establishing normal mean values of the parameters of the electrocardiographic curve and their standard deviations 50 male guinea pigs were studied. The directions of temporary vectors of atrial (AP) and ventricular (AQRS) depolarization times, and ventricular repolarization time (AT) were determined, and the position of the heart was evaluated. In all animals limb leads I, II, III, aVR, aVL, aVF were used, and in 38 animals additionally the precordial leads V1, V2, V3, V4, V5, V6 were applied. The investigations were done by a non-invasive method with a specially designed plate making possible immobilization of the animals in supine position under general anaesthesia with urethane. In 10% of the animals abnormalities were detected in the ECG curve and these guinea pigs were eliminated from further analysis. The investigations showed that, after consideration given to the differences in the ECG curves in relation to man, guinea pigs might be used for preclinical cardiological studies.     

Rearing of germfree guinea pigs and establishment of an SPF guinea pig colony]

New born guinea pigs of Hartley strain derived by hysterectomy were fed commercial pellets, cow's milk, egg yolk and vitamin mixture since 0 days of age, when they were kept at 31 +/- 1 degrees C. Out of 33 animals, 30 were reared for 40 days under aseptic state and they were transfered to a barrierred facility to establish an SPF colony free from Bordetella bronchiseptica, Streptococcus zooepidemicus (Animal C), Salmonella spp., Tyzzer's organisms, Mycoplasma spp., Reo 3 virus, Sendai virus, Eimeria spp., Chirodiscoides caviae and Gliriocola porcelli.