Development of resistance to reinfection by Clonorchis sinensis in rats

We investigated the induction of resistance to Clonorchis sinensis infection by prior infection in rat and hamster models. Animals were challenged with C. sinensis metacercariae, then treated with praziquantel and reinfected. Worm recovery rate in reinfected animals was used to estimate resistance to reinfection. The determined resistance rates to reinfection in rats and hamsters were 97.7% and 10.3%, respectively. In rats, cure from the primary infection of C. sinensis increased resistant to reinfection, and the greater the worm burden and the longer the duration of primary infection, the higher was the resistance rate. For primary infection doses of 10, 40 and 100 metacercariae per rat, the resistance rates were 87.4%, 93.8% and 98.4%, respectively. The resistance rates in rats after 2 or 8-week primary infection were 78.7% and 95.3%, respectively. All worms recovered from reinfected rats were immature. When cured rats were administered with methylprednisolone, resistance to reinfection became impaired. These findings indicate that rats develop a high degree of resistance to reinfection by C. sinensis after cure. The growths and maturations of reinfected worms were also impaired.     

Karyotypes of Pneumocystis carinii derived from several mammals

Pneumocystis carinii is the most important opportunistic pathogen of humans in the world. Pneumocystis carinii is experimentally detected in the lungs of rats, mice, rabbits, and monkeys, however, the organisms from different mammals are identical in microscopic morphology. The present study tried to find out more mammalian hosts of P. carinii and also to differentiate the organisms from different mammals by karyotyping. Rats, mice, hamsters, rabbits, cats, and dogs were successfully infected by P. carinii, but guinea pigs and pigs were not. Karyotype of P. carinii from rabbits showed similar size range of chromosomes with that of the prototype, but in different pattern. The patterns from cats and dogs were also different from that of rats. The present study confirms that cats and dogs are infected by P. carinii and at least total three karyotype strains of P. carinii are proven in Korea.     

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.     

Sensibilité comparée de divers animaux de laboratoire à l'infection par instillations nasales de la phase saprophytique d'Emmonsia crescens Emmons & Jellison, 1960: Fréquence et intensité du parasitisme,réactions histopathologiques

Comparative observations were made on the development of Emmonsia crescens in the lungs of laboratory rats and mice, golden hamsters and guinea pigs after a nasal instillation of a heavy suspension of the saprophytic phase of the fungus. 95% of 80 experimental rats were found to be parasited against 80% of 200 inoculated mice, while only 30% of 70 hamsters and all of 4 guinea pigs showed an infection. The lungs of the mice, rats and guinea pigs were frequently more heavily infected than those of the hamsters. In addition, the adiaspores obtained from the mice and rats had, on average, a diameter double those from the hamsters and their walls were thicker. Thus, the laboratory mice and rats were shown to be better hosts of E. crescens than were golden hamsters.     

Relationship between susceptibility and immune response to staphylococcal exfoliative toxin A in mammalian species

Staphylococcal exfoliative toxin A (ETA) had a splitting effect at the granular layer of skin in humans and neonatal mice, but not in rabbits, guinea pigs, golden hamsters, or rats. Besides its splitting effect, ETA could stimulate productions of neutralizing antibody to ETA in rabbits, rats and B10D2 mice, but not in golden hamsters, guinea pigs, or ICR, HRS/J, and C57BL/10 mice. In our epidemiological investigation of human sera, the percentage of antibody to ETA in sera obtained from patients with impetigo (8%) was lower than those in sera of healthy males (23%) and females (29%). The relationship between susceptibility and immune response to ETA in these mammalians could be divided into three groups: the possession of resistant skin and high production of antibody to ETA; the possession of resistant skin and low production of antibody to ETA; the possession of sensitive skin and various titers of antibody to ETA.     

Respiratory measurements of unsedated small laboratory mammals using nonrebreathing valves

The respiratory frequency, tidal volume, minute volume, oxygen uptake and carbon dioxide output of unsedated hamsters, rats, guinea pigs and rabbits were measured to obtain comparative data and to evaluate the performance of those species as unsedated subjects. The animals were trained to remain stationary and breathe through nonrebreathing valves while expired gas was collected and respiratory frequency was monitored. Measurements of dogs also were conducted to obtained comparative data by similar methods. Hamsters were readily trained and performed reliably during repeated trials. Rats and guinea pigs were more difficult to train and performed erratically. The rabbits' performance was intermediate between that of hamsters and the other species. The back pressures caused by the small animal nonrebreathing valves at estimated peak flow rates were either similar to or less than those encountered by dogs. Measured respiratory values were compared to values predicted by published equations based on body weight. Data from this study generally reflected species differences related to body weight and metabolic rate similar to those predicted by the equations, but values from the four smaller species also may have reflected differences related to behavior.     

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)     

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.     

Qualitative and quantitative differences in normal vaginal flora of conventionally reared mice, rats, hamsters, rabbits, and dogs

We examined quantitatively the vaginal flora of conventionally reared mice, rats, hamsters, rabbits and dogs, species that are widely used as laboratory animals. Vaginal specimens were examined according to the method of analyzing intestinal flora (Mitsuoka's procedure). The total number of bacteria (aerobes and anaerobes) and the prevalence of specific bacteria were determined. The total number of bacteria was highest during estrus and lowest during diestrus or anestrus in mice, rats, hamsters, and dogs. The most predominant bacteria during estrus were streptococci in mice; gram-negative rods (GNR), streptococci, and members of the family Bacteroidaceae in rats; GNR, Bacteroidaceae and gram-positive anaerobic cocci in hamsters, and Bacteroidaceae in dogs. The increase in the total number of bacteria during estrus was caused by an increase of predominant bacteria in the vagina. Aerobes were more predominant than anaerobes in mice, and number of aerobes was comparable to that of anaerobes in rats and dogs. On the other hand, in hamsters, anaerobes were more predominant than aerobes and the total number of bacteria was highest among the laboratory animals (mice, rats, hamsters, rabbits, and dogs). However, in rabbits, bacteria were not isolated from about 90% of the vaginal specimens. Rabbits do not have cyclic reproductive stages and are usually in precoital status in the laboratory. In precoital rabbits, vaginal epithelium manifests few signs of secretion. Therefore, we suspect that the vaginal environment in precoital rabbits is comparable to that during diestrus or anestrus in mice, rats, hamsters, and dogs. These results suggest that the vaginal flora of laboratory animals is influenced by the estrous cycle, and probably by mucous secretion. Our data imply that vaginal flora differ among laboratory animals species, and researchers need to take into consideration the estrous cycle of laboratory animals when studying their vaginal flora.     

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.     

State of pulmonary surfactant in different species of animals

The authors have shown that pulmonary surfactand activity in mice, rats, guinea pigs, hamsters, rabbits and dogs was within the normal limits with the fluctation of the air vesicle stability coefficient of from 0.84 to 0.93. Differences revealed in the surface active substance in different animal species depend on the frequency, expression and the nature of spontaneous pulmonary pathology. The data obtained can be used as the initial ones to study the surface pulmonary activity system under various experimentally-induced conditions of the pulmonary tissue.     

Chylomicron metabolism. Chylomicron uptake by bone marrow in different animal species

Previously it was shown in rabbits that 20-40% of the injected dose of chylomicrons was cleared from the plasma by perisinusoidal bone marrow macrophages. The present study was undertaken to determine whether the bone marrow of other species also cleared significant amounts of chylomicrons. Canine chylomicrons, labeled in vivo with [14C]cholesterol and [3H] retinol, were injected into marmosets (a small, New World primate), rats, guinea pigs, and dogs. Plasma clearance and tissue uptake of chylomicrons in these species were contrasted with results obtained in rabbits in parallel studies. The chylomicrons were cleared rapidly from the plasma in all animals; the plasma clearance of chylomicrons was faster in rats, guinea pigs, and dogs compared with their clearance from the plasma of rabbits and marmosets. The liver was a major site responsible for the uptake of these lipoproteins in all species. However, as in rabbits, the bone marrow of marmosets accounted for significant levels of chylomicron uptake. The uptake by the marmoset bone marrow ranged from one-fifth to one-half the levels seen in the liver. The marmoset bone marrow also took up chylomicron remnants. Perisinusoidal macrophages protruding through the endothelial cells into the marrow sinuses were responsible for the accumulation of the chylomicrons in the marmoset bone marrow, as determined by electron microscopy. In contrast to marmosets, chylomicron clearance by the bone marrow of rats, guinea pigs, and dogs was much less, and the spleen in rats and guinea pigs took up a large fraction of chylomicrons. The uptake of chylomicrons by the non-human primate (the marmoset), in association with the observation that triglyceride-rich lipoproteins accumulate in bone marrow macrophages in patients with type I, III, or V hyperlipoproteinemia, suggests that in humans the bone marrow may clear chylomicrons from the circulation. It is reasonable to speculate that chylomicrons have a role in the delivery of lipids to the bone marrow as a source of energy and for membrane biosynthesis or in the delivery of fat-soluble vitamins.     

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.     

Saprophytic occurrence of Trichophyton mentagrophytes and Microsporum gypseum in the coats of healthy laboratory animals

A group of 199 healthy laboratory animals, comprising 63 guinea pigs; 58 white mice. 47 rats and 31 rabbits, was sampled for the presence of pathogenic dermatophytes. T. mentagrophytes, var. granulare, was isolated in 10% (5-guinea pigs, 6 mice, 6 rats and 2 rabbits) and M. gypseum was found in 7 animals (3 guinea pigs, 3 mice and one rat). No ringworm lesions were observed in the respective animals. This is the first report on such findings in Israel.     

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.     

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.     

A heterophile antigen associated with experimental toxoplasmosis

The biological characteristics of a heterophile protein (HP) in peritoneal exudate from mice, hamsters, rats, and guinea pigs infected with Toxoplasma gondii were studied by immunofluorescence, immunoelectrophoresis and immunodiffusion techniques using specific antisera raised in rabbits. HP of mice had the highest antigenicity, HP of hamsters and rats had intermediate antigenicity and HP of guinea pigs had the lowest antigenicity. HP was found in normal peritoneal exudates from mice, hamsters and rats inoculated with paraffin oil instead of T. gondii and in normal guinea pig serum. HP was detected by the fluorescent antibody technique on the surface of T. gondii in peritoneal exudates of mice, but not on mouse peritoneal cells, and by the indirect fluorescent antibody technique on L cells infected with T. gondii and on free Toxoplasma derived from them, but not on uninfected L cells. T. gondii could make host cells produce HP to cover its surface for protection. The relation between HP from host cells and T. gondii is discussed.     

Reaction of various experimental animals to exposure to acetylcholine or histamine, and morphological observations of bronchial smooth muscle

We investigated the sensitivity of the airway of various experimental animals to acetylcholine (ACh) and histamine (Hist). The experimental animals were exposed to 0.1% ACh or 0.05% Hist. Guinea pigs and rabbits exhibited an asthmatic reaction to both chemicals, but rabbits seemed to have a milder reaction than guinea pigs to both chemicals. Mice, rats and hamsters showed no reaction. We then performed a morphological study of the airways of 5 species in order to clarify the reason for their different reactivities to ACh and Hist. In the morphological study, abundant smooth muscle could be seen in the terminal bronchioles and respiratory bronchioles of guinea pigs and rabbits. In contrast, animals of other species had little smooth muscle in either site. Mice had no respiratory bronchioles. Consequently, we concluded that there is a high correlation between sensitivity to ACh and Hist and the extent of smooth muscle distribution around the airway.     

Life cycle and host specificity of Amblyomma triste (Acari: Ixodidae) under laboratory conditions

We report biological data of two generations of Amblyomma triste in laboratory and compared the suitability of different host species. Infestations by larval and nymphal stages were performed on guinea pigs (Cavia porcellus), chickens (Gallus gallus), rats (Rattus norvegicus), rabbits (Oryctolagus cuniculus), wild mice (Calomys callosus), dogs (Canis familiaris) and capybaras (Hydrochaeris hydrochaeris). Infestations by adult ticks were performed on dogs, capybaras and rabbits. Tick developmental periods were observed in an incubator at 27 degrees C and RH 90%. Guinea pigs were the most suitable hosts for larvae and nymphs, followed by chickens. The remaining host species were less suitable for immature ticks as fewer engorged ticks were recovered from them. Mean larval feeding periods varied from 3.8 to 4.7 d between different host species. Mean larval premolt periods ranged from 8.9 to 10.4 d. Nymphal mean feeding periods varied from 4.2 to 6.2 d for ticks fed on different host species. Premolt period of male nymphs (mean: 15.4 d) was significantly longer than that of female nymphs (14.7 d). Female nymphs were significantly heavier than male nymphs. The overall sex ratio of the adult ticks emerged from nymphs was 0.9:1 (M:F). Capybaras were the most suitable host for the tick adult stage as significantly more engorged females were recovered from them and these females were significantly heavier than those recovered from dogs or rabbits. The life cycle of A. triste in laboratory could be completed in an average period of 155 d. The potential role of guinea pigs, birds and capybaras, as hosts for A. triste in nature, is discussed.     

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.