Dermatophytes isolated from laboratory animals

In order to determine the presence of dermatophytes in healthy skin, 200 animals from the animal house of Faculty of Medicine, U.N.A.M., were studied; these were 50 rats, 50 rabbits, 50 mice, and 50 guinea pigs. Out of these 200 animals, 29.5% had positive isolation of Trichophyton mentagrophytes, var. lacticolor. The frequency variation was: rats, 68%; rabbits, 36%; mice, 8%; and guinea pigs, 6%. Male rats and male rabbits, had the higher incidence of positives. The epidemiologic repercussion of these and the significance to use these animals in biomedical investigation is discussed.     

Pharmacokinetics of fusidic acid in laboratory animals.

The ability of evaluate the efficacy of fusidic acid in animal models of infectious disease is limited by the absence of pharmacokinetic data for the agent in laboratory animals. In our study, aspects of fusidic acid pharmacokinetics were compared in rats (Rattus norwegicus), mice (Mus musculus), rabbits (Oryctolagus cuniculus), and guinea pigs (Cavia porcellus). Sodium fusidate was poorly absorbed after oral administration to rats, although limited absorption occurred in guinea pigs, mice, and rabbits. Subcutaneous injections of diethanolamine fusidate to laboratory rats, however, achieved a serum profile similar to that observed in humans. There was no evidence of drug accumulation in rats given repeated subcutaneous doses of diethanolamine fusidate during a 4-day period, but rabbits showed clear evidence of a cumulative effect.     

Susceptibility of experimental animals to reinfection with Clonorchis sinensis

The present study observed the resistance to reinfection with Clonorchis sinensis in various experimental animals including mice, guinea pigs, rabbits, and dogs, as well as rats and hamsters. The resistance rates to reinfection in rats, mice, hamsters, guinea pigs, rabbits, and dogs were 79.7%, 58.0%, -12.6%, 54.8%, 62.6%, and 6.0%, respectively. Worms recovered from reinfected rats and mice were immature, and significantly smaller than those from the primarily infected (P < 0.01), whereas those from other animals were fully matured to adults. These findings indicate that the protective response against reinfection with C. sinensis is prominent in rats and mice, and that they may be a good animal model to investigate the mechanism of resistance to reinfection with C. sinensis.     

Pathogenicity for several laboratory animals of toxoplasma oocysts originated from naturally infected cats.

The pathogenicity of four strains, O-1, O-2, O-3, and O-4, of Toxoplasma isolated in the form of oocyst from the feces of naturally infected cats was examined for such laboratory animals as mice, rats, rabbits, guinea pigs, and dogs, in comparison with that of the Beverley strain. Suspensions of seven graded doses of oocysts of each strain ranging from 1.0 X 10(-1) to 1.0 X 10(5) were inoculated orally into seven groups of five mice each. The O-1, O-2, and O-3 strains were as pathogenic for mice as the Beverley strain, but the O-4 strain was not so pathogenic as any other strain. Rats, rabbits, guinea pigs, and dogs were inoculated orally with around 1.0 X 10(5) oocysts. The four O strains were not so severly pathogenic for rats and rabbits as to cause death. The O-2 and O-3 strains showed strong pathogenicity for guinea pigs, almost all of which, when inoculated with them, died after manifesting severe clinical symptoms. The pathogenicity of the O-1 and O-2 strains showed essentially the same tendency for dogs as for any other animal. In inoculation with oocysts, as well as with proliferative forms or cysts, the same pathogenicity was not observed in different strains, even if the same species of host animals was used. On the contrary, the same pathogenicity was not always found even in one strain when a different species of animals was used.     

Angiostrongylus cantonensis: Development following pulmonary arterial transfers into permissive and nonpermissive hosts

The survival, growth, and egg-laying capacity of young adult Angiostrongylus cantonensis, surgically transferred from intracranial sites into pulmonary arteries, were studied. A variety of experimental animals (rats, guinea pigs, mice, and mastomys) were chosen as donor animals and as recipient hosts (rats, guinea pigs, and rabbits). These species were specifically chosen to span the spectrum of host permissiveness relative to worm development in an attempt to understand the mechanisms which underlie species-dependent resistance. Recipient animals were monitored not only for the development of parasites per se but also for antibody production and histopathologic changes. The results indicated that these procedures were technically feasible, with good worm development following intra-rat transfers, as early as 15 days after initial exposure. Studies were performed to analyze the constraints of development both on initial, i.e., prelung and subsequent i.e., postlung development. When worms were obtained from permissive species such as rat or mastomys, transfer into rats resulted in good growth and development; however, worms which developed initially in exposed mice or guinea pigs developed less well in the rat. Conversely, worms which developed initially in permissive host such as the rat, when transferred into a variety of less permissive hosts such as the guinea pig and rabbit, apparently did not survive and caused significant morbidity and mortality within the nonpermissive host. Histopathologic evaluation revealed a strong eosinophilic perivascular and peribronchiolar infiltration as well as granulomatous reactions surrounding the worms in the lungs of recipient guinea pigs and rabbits, changes not observed in the lungs of permissive rat recipients. As reaginic antibody responses were also more prominent in nonpermissive than in permissive animals, it is possible that IgE responses may be more directly related to the phenomenon of morbidity and/or permissiveness than are other aspects of immune response. In support of this contention was the finding of nearly equivalent hemagglutinating antibody production between permissive rats and nonpermissive guinea pigs and rabbits.     

The activities and intracellular distributions of enzymes of carbohydrate, lipid and ketone-body metabolism in lactating mammary glands from ruminants and non-ruminants.

1. The activities of several enzymes of carbohydrate, lipid, acetate and ketone-body metabolism were measured in lactating mammary glands from rats, mice, rabbits, guinea pigs, sows, sheep, cows and goats. The intracellular distributions of many of the enzymes were measured by fractional extraction. 2. Acetyl-CoA synthetase was predominantly cytoplasmic in rats and guinea pigs, but was more mitochondrial in the other species. The different location of this enzyme in rats and mice is discussed in relation to the disposal of reducing equivalents. 3. 3-Oxo acid CoA-transferase and acetoacetyl-CoA thiolase assayed at 600 microM-CoA were predominantly mitochondrial in all species investigated. Acetoacetyl-CoA thiolase assayed at 8 microM-CoA was predominantly cytoplasmic, except in rabbits and guinea pigs. Ruminants appeared to possess little, if any, of the cytoplasmic enzyme. 4. The activities and distributions of NADP-isocitrate dehydrogenase were consistent with a role in supplying cytoplasmic NADPH in ruminant tissue, and indicated that this system may also occur in guinea pigs.     

Correlation of Propionibacterium acnes Populations with the Presence of Triglycerides on Nonhuman Skin

The skins of mice, rats, rabbits, sheep, guinea pigs, and dogs were cultured for Propionibacterium acnes. Only the sebaceous regions (perianal gland) of guinea pigs harbored a significant P. acnes population. Analysis of the lipid from this region revealed a significant percentage of triglycerides, compounds lacking in the sebum of the other animals.     

Damaging action of dithizone on insulin-releasing cells

Alterative action of dithizone was investigated in the experiments on various species of animals (fish, frogs, pigeons, mice, guinea pigs, golden hamsters, rats, rabbits, cats and dogs). The data received support the previously advanced suggestion that unsaturated (electrophilic) zinc complex formation is the basic mechanism of the alterative chelant's action.     

Quantitative gas-liquid chromatographic analysis of rodent milk triglycerides

A comparison has been made of the milk and adipose tissue triglycerides of rabbits and guinea pigs provided with one diet and of rats and mice provided with another. Both intact triglycerides and component fatty acids were analyzed by gas-liquid chromatography. Good correlation of the data obtained by the two techniques was obtained by calculating the average chain length of the fatty acid moieties. Little difference was found in the triglyceride composition of the adipose tissue of the different species. However, wide variation in the triglyceride composition of the milk was found between the species: the average fatty acid chain length in milk was 11.7 for rabbits, 14.2 for rats, 15.3 for mice, and 17.2 for guinea pigs. The corresponding values for adipose tissue were in the range 16.9-17.4 in all animals. The significance of enzymes that synthesize short-chain fatty acids in mammary gland is discussed.     

Comparison of tracheal mucous transport in rats, guinea pigs, rabbits, and dogs

Tracheal mucous transport was measured using similar techniques in several species. One- to 10-microliter quantities of 99mTc-macroaggregated albumin (99mTc-MAA) were instilled via oral intubation in the distal trachea of rats, rabbits, and dogs. Tracheostomies were used for the instillation in guinea pigs. All animals were anesthetized with halothane for the instillation and allowed to recover immediately in restrainers. Clearance of the 99mTc-MAA in rats and guinea pigs was measured by a slit-collimated NaI scanner. In rabbits and dogs a series of gamma-camera scintiphotos were taken. Clearance was faster and more efficient in dogs than in the other species. No significant differences existed among the rats, rabbits, and guinea pigs in the percentages of the originally deposited material remaining at the instillation site after 1 h (P greater than 0.2). Mean values and standard deviations were 83 +/- 23%, 81 +/- 22% and 70 +/- 20% for rats, guinea pigs, and rabbits, respectively. However, in the dogs a mean of 14 +/- 12% remained at the original site of deposition after only 25 min indicating much more rapid clearance. Mean leading-edge velocities were 9.8 +/- 2.1 (SD) for dogs, 3.2 +/- 1.1 for rabbits, 2.7 +/- 1.4 for guinea pigs, and 1.9 +/- 0.7 mm/min for rats. Clearance patterns qualitatively among the species. In dogs the material moved as a few discrete boluses, whereas in the other species the activity spread toward the larynx. The relatively slow mucous transport of rats, rabbits, and guinea pigs could have important implications in inhalation toxicological studies.     

The induction of suppressor T cells by lipopolysaccharide in human peripheral blood lymphocyte cultures in the presence of fetal calf serum

Alveolar macrophages (AM) were collected by repeated endobronchial lavage from mice, rats, guinea pigs, and rabbits, and titrated into cultures of mitogen-stimulated syngeneic or autochthonous lymphocytes. Significant species differences were detected in regard to AM activity in the cultures. AM from guinea pigs and mice stimulated PHA-induced lymphoproliferation, while those from rats and rabbits were inhibitory; blood or peritoneal macrophages were not inhibitory in any of the species examined.     

The fate of cyclamate in man and other species

1. (14)C-labelled cyclamate has been administered to guinea pigs, rabbits, rats and humans. When given orally to these species on a cyclamate-free diet, cyclamate is excreted unchanged. In guinea pigs some 65% of a single dose is excreted in the urine and 30% in the faeces, the corresponding values for rats being 40 and 50%, for man, 30-50% and 40-60%, and for rabbits, 90 and 5%, the excretion being over a period of 2-3 days. 2. Cyclamate appears to be readily absorbed by rabbits but less readily by guinea pigs, rats and humans. 3. If these animals, including man, are placed on a diet containing cyclamate they develop the ability to convert orally administered cyclamate into cyclohexylamine and consequently into the metabolites of the latter. The extent to which this ability develops is variable, the development occurring more readily in rats than in rabbits or guinea pigs. In three human subjects, one developed the ability quite markedly in 10 days whereas two others did not in 30 days. Removal of the cyclamate from the diet caused a diminution in the ability to convert cyclamate into the amine. 4. In rats that had developed the ability to metabolize orally administered cyclamate, intraperitoneally injected cyclamate was not metabolized and was excreted unchanged in the urine. The biliary excretion of injected cyclamate in rats was very small, i.e. about 0.3% of the dose. 5. The ability of animals to convert cyclamate into cyclohexylamine appears to depend upon a continuous intake of cyclamate and on some factor in the gastrointestinal tract, probably the gut flora.     

Pathogenesis of CAR bacillus in rabbits, guinea pigs, Syrian hamsters, and mice.

Cilia-associated respiratory (CAR) bacillus isolated from infected mice (designated, CBM) and propagated in embryonated chicken eggs was inoculated intranasally in rabbits (Oryctolagus cuniculus), guinea pigs (Cavia porcellus), hamsters (Mesocricetus auratus) and mice (Mus musculus). Gross and microscopic lesions, localization of CBM antigen in the respiratory tract, development of antibody, and ability to reisolate the CAR bacillus were studied in animals killed at 2-, 4-, or 8-week intervals postinoculation (PI). In rabbits, although no histopathological changes were observed in the respiratory tract, CBM antigen was detected on the ciliated epithelium of the respiratory tract, and serum CBM antibody was also detected 4 and 8 weeks PI. In guinea pigs, no histopathological changes were noted, CBM antigen was detected in the respiratory tract 2 and 4 weeks PI but not 8 weeks PI, and serum CBM antibody was detected 4 and 8 weeks PI. In hamsters, mononuclear cell proliferation in the submucosa of the bronchus and trachea was observed 8 weeks PI. CBM antigen was detected at first in the nasal cavity 2 weeks PI and in the lower respiratory tract 4 and 8 weeks PI and serum CBM antibody was detected 4 and 8 weeks PI. In mice, histopathological changes, CBM antigen and CBM antibody were observed. CBM was reisolated from the tracheal washouts of hamsters and mice 8 weeks PI but not from those of rabbits and guinea pigs. These results confirm and extend previous reports of experimentally-induced CAR bacillus infection in mice, guinea pigs, and rabbits. To this list of susceptible laboratory animals, we now add hamsters.(ABSTRACT TRUNCATED AT 250 WORDS)     

Susceptibility of various animals to Pneumocystis carinii infection.

Pneumocystis carinii (Pc) is an important opportunistic pathogen of immune compromised hosts, and is known to infect various animals. The present study observed the infection status of 6 mammals and 3 strains of albino rats with Pc after suppression of their immunity. Methyl-prednisolone was injected once a week and tetracycline was supplied with water for 5 to 21 weeks. Hamsters, guinea pigs, rabbits, dogs, cats and pigs were negative by impression smear, and only the rats were found infected by Pc. All of the three strains of rats, Sprague-Dawley(SD), Wistar(W) and Fisher(F), were infected by Pc but W rats showed heavier degree of infection in earlier period than F or SD rats. The present findings suggest that W rat is the best among the animals used in the present study for production of Pc.     

Immunocytochemical studies on parafollicular cells of various mammals

Using specific antisera, calcitonin, calcitonin gene-related peptide (CGRP), somatostatin as well as neuron-specific enolase, chromogranin, secretory peptide I and calbindin (vitamin D-dependent calcium-binding protein) were looked for in parafollicular cells of rats, Syrian hamsters, Mongolian gerbils, mice, guinea pigs, rabbits and pigs. Calcitonin and CGRP were most invariably present in various species. Somatostatin was absent in mice and Mongolian gerbils and present in variable amounts in the remaining species. Neuron-specific enolase could not be detected in rabbits, while in the pigs and the Mongolian gerbils it could be demonstrated only in some parafollicular cells. Calbindin was present exclusively in parafollicular cells of guinea pigs. Chromogranin and secretory protein-I were present only in some animal species.     

Comparative respiratory system mechanics in rodents.

Because of the wide utilization of rodents as animal models in respiratory research and the limited data on measurements of respiratory input impedance (Zrs) in small animals, we measured Zrs between 0.25 and 9.125 Hz at different levels (0-7 hPa) of positive end-expiratory pressure (PEEP) in mice, rats, guinea pigs, and rabbits using a computer-controlled small-animal ventilator (Schuessler TF and Bates JHT, IEEE Trans Biomed Eng 42: 860-866, 1995). Zrs was fitted with a model, including a Newtonian resistance (R) and inertance in series with a constant-phase tissue compartment characterized by tissue damping (Gti) and elastance (Hti) parameters. Inertance was negligible in all cases. R, Gti, and Hti were normalized to body weight, yielding normalized R, Gti, and Hti (NHti), respectively. Normalized R tended to decrease slightly with PEEP and increased with animal size. Normalized Gti had a minimal dependence on PEEP. NHti decreased with increasing PEEP, reaching a minimum at approximately 5 hPa in all species except mice. NHti was also higher in mice and rabbits compared with guinea pigs and rats at low PEEPs, which we conclude is probably due to a relatively smaller air space volume in mice and rabbits. Our data also suggest that smaller rodents have proportionately wider airways than do larger animals. We conclude that a detailed, comparative study of respiratory system mechanics shows some evidence of structural differences among the lungs of various species but that, in general, rodent lungs obey scaling laws similar to those described in other species.     

Intramitochondrial helical filaments in medullary tubules of the rat kidney

Characteristic helical filaments were frequently found within dilated intracristal spaces of the mitochondria in epithelial cells of renal medullary tubules of normal rats of both sexes. These filaments had a helical structure with right-handed rotation. The approximate dimensions were 4 nm in thickness, 13 nm in helical diameter, and 16 nm in pitch. The filaments were common in all strains of rats examined in the present study but not in animals of other species including mice, guinea pigs, golden hamsters, Mongolian gerbils, house musk shrews, and rabbits. In Sprague-Dawley strain rats, the filaments were found not only in animals of all ages but also in 6-week-old germ-free animals and fetuses at the 18th day of gestation. Even in the same rats, the helical filaments were completely absent in the cortical tubules.     

Trypsin inhibitors in guinea pig plasma: isolation and characterization of contrapsin and two isoforms of alpha-1-antiproteinase and acute phase response of four major trypsin inhibitors

Contrapsin and two isoforms, F (fast) and S (slow), of alpha-1-antiproteinase (also called alpha-1-proteinase inhibitor) were isolated in an apparently homogeneous state from plasma of inflamed guinea pigs. Contrapsin inactivated trypsin, but did not significantly affect chymotrypsin, pancreatic elastase, or pancreatic kallikrein. On the other hand, both isoforms of alpha-1-antiproteinase inhibited trypsin, chymotrypsin, and elastase, but not plasma or pancreatic kallikrein. The S isoform of alpha-1-antiproteinase was present in barely detectable amounts in healthy animals, but increased markedly when the acute-phase reaction was induced by subcutaneous injection of turpentine. On the other hand, the plasma levels of the F isoform, contrapsin, and alpha-macroglobulin showed moderate (1.5 to 2.3-fold) elevation during the acute-phase reaction. In contrast to the previous findings that rats and rabbits contain two different alpha-macroglobulins, one of which is an acute-phase reactant while the other is not, inflamed guinea pigs contained only one species of alpha-macroglobulin. Murinoglobulin, the most prominent acute-phase negative protein in both mice and rats, showed no significant change in guinea pigs. These results indicate that guinea pig plasma contains four major trypsin inhibitors, i.e., contrapsin, alpha-1-antiproteinase, alpha-macroglobulin, and murinoglobulin, the properties of which are very similar to those of the respective mouse homologues, but that the acute-phase response of these inhibitors differs greatly from that of the homologous proteins in rats or mice.     

Biological features of the skin of the pika, Ochotona rufescens rufescens--concentration of histamine in the skin

The quantity of histamine and the number of mast cells in the skin of the pika were measured and compared with rabbits, guinea pigs and rats. The ranking of regional histamine levels in the skin of the pika was: perianal region greater than abdomen greater than interscapular region = back greater than lumbus greater than head greater than auricle, and the average value of the 7 regions was 22.6 micrograms/g. The level of histamine in the 6 regions, except the auricle, was 2-5 times that of rabbits and guinea pigs. In the auricle of each of the 4 kinds of animal (pika, rabbit, guinea pig and rat), the levels were almost identical. With respect to histamine levels, those in the pika resembled those in rats. The number of mast cells in the skin of the pika was less than in rats, and was greater than that in rabbits and guinea pigs. The average value was 9.9/mm2.     

PCO(2) in the large intestine of mice, rats, guinea pigs, and dogs and effects of the dietary substrate.

PCO(2) in the lumen and serosa of cecum and colon was measured in rats, guinea pigs, and dogs to examine the relationship between serosal PCO(2) and the incidence of intestinal necrotic lesions after administration of gas-carrier contrast agents in rodents. The effects of the dietary substrate were tested in a group of mice maintained on a diet based on glucose as the only carbohydrate source. The anesthetic used was a fentanyl-fluanison-midazolam mixture (rodents) and pentobarbital (dogs). PCO(2) was measured in vivo and postmortem, and the kinetics of the postmortem serosal PCO(2) [transmural CO(2) flux (J(CO(2)))] was calculated. PCO(2) in the cecal serosa and lumen, respectively, was 64 +/- 4 and 392 +/- 18 Torr in rats, 67 +/- 3 and 276 +/- 17 Torr in guinea pigs, and 73 +/- 6 and 137 +/- 7 Torr in mice on glucose-based diet. In the colon serosa and lumen of dogs, PCO(2) was 30 +/- 6 and 523 +/- 67 Torr, respectively. Serosal PCO(2) increased rapidly after death in rats and slower in guinea pigs and mice, and the slowest change was observed in dogs. Compared with dogs, serosal PCO(2) and J(CO(2)) of rats and guinea pigs were significantly higher. Serosal PCO(2) of guinea pigs was similar to that of rats, whereas the J(CO(2)) of guinea pigs was significantly lower. These data suggest a causal relationship between the ability of the cecal and colonic wall to act as a barrier to CO(2) diffusion and the presence of characteristic gas-carrier contrast agent-induced intestinal lesions in mice and rats and their absence in guinea pigs, dogs, and other species.