Various Species Of Laboratory Animals Research Articles

Artificial Device for Extracorporeal Blood Oxygenation in Rats

Blood oxygenation devices are an essential component of any cardiopulomonary bypass circuit in various species of laboratory animals. When using larger animals like dogs or pigs, the human and pediatric blood oxygenators could be easily used, but the disadvantage of these species is the scarcity of biochemical and genetic assays for experimental follow-up. However, small rodents like rats have plenty of biochemical assays, but their size requires special oxygenators adapted for their small blood volume and often primed with blood of another animal or other physiological solution. We showed the new design of a blood oxygenator with direct blood-gas contact in an open circuit, specially designed for rats in which the blood oxygenation takes place in a slowly rotating plastic tube with blood spread onto its inner walls in a thin layer. The oxygenator is simple and efficient, does not require priming with the blood of another rat, has a small dead volume, is reusable, and easy to clean and sterilize.

Heterotopic cardiomyocytes in the wall of pulmonary vessels in experimental animals.

Heterotopic cardiomyocytes (CMC) have been described in the wall of pulmonary veins including intraparenchymatous branches, in various species of laboratory animals. Brief note is given here of their morphology including electron microscopy and immunohistological findings. From the current literature hints concerning arrhythmogenic activity of heterotopic CMC in pulmonary vessels in the possible initiation of atrial tachyarrhythmia and fibrillation are also mentioned.

Immunohistochemical Localization of Chromogranin A in Normal Tissues from Laboratory Animals

To analyze the distribution of Chromogranin A in endocrine cells of various species of laboratory animals (dog, gerbil, guinea pig, hamster, monkey, mouse, and fetal, neonatal, and adult rats), normal tissues were stained immunohistochemically with polyclonal anti-bovine Chromogranin A antiserum (SP-1). Selected tissues (pituitary, adrenal, thyroid, parathyroid, pancreas, brain, peripheral nerve, stomach, small and large intestine, bone marrow, spleen, thymus, lymph node, and liver) from these species and from the rabbit were stained with two monoclonal anti-human Chromogranin A antibodies (LK2H10 and PHE5) to compare the immunoreactivities of the monoclonal antibodies and polyclonal antiserum. Staining with the polyclonal antiserum (SP-1) resulted in a broader spectrum of immunoreactivity but had more nonspecific background staining than either monoclonal antibody. Immunoreactivity and staining intensity with SP-1 varied between species, but most endocrine tissues (pituitary cells in the anterior and intermediate lobes, thyroid "C" cells, adrenal medulla, parathyroid, pancreatic islets, and enterochromaffin cells) from most species stained positively. In some species, pancreatic alpha cells stained more intensely, and two populations of adrenal medullary cells with different staining intensities were observed. Sciatic nerve (axonal area) was immunoreactive with monoclonal antibodies and/or the polyclonal antiserum in several species. The spectrum of immunoreactive tissues from fetal and neonatal rats increased with age. There was good cross-reactivity between species with SP-1, but not with either LK2H10 or PHE5. These results indicate that many endocrine cells with secretory granules in laboratory animals express Chromogranin A and that a polyclonal antiserum, such as SP-1, is more sensitive in detecting this protein in various species than monoclonal antibodies such as LK2H10 or PHE5.

The automated bone marrow micronucleus test

A new technology is presented which offers high-quality slides enabling the fully automated scoring of large quantities of erythrocytic cells for micronuclei by computerized image analysis. The techniques are applicable to bone marrow specimens as well as to peripheral blood obtained from various species of laboratory animals as well as from man. The key steps leading to this improved slide quality are the total removal of nucleated hematopoietic cells and the production of ‘flat’ cells by cytocentrifugation on polylysine-coated slides. The new procedures also allow the quantitative elimination of artifact-producing leukocytic granules from the rat bone marrow, even for the Fischer-344 strain, thus making the rat micronucleus test an attractive system for routine purposes in genetic toxicology. In addition, the proportion of immature erythrocytes can, if desired, be increased to more than 90% by using a Percoll step-gradient. This greatly facilitates the peripheral blood micronucleus test in laboratory animals as well as in (splenectomized) humans. First results, using peripheral blood from 2 rat strains, indicate that the immature erythrocyte population is very useful for micronucleus analysis, which encourages the development of a rat peripheral blood micronucleus test. This is an interesting application because it allows repeated testing in the same animals, resulting in fewer rats being needed, as no separate control groups are necessary. A further advantage is the possibility of concomitantly using rats from an ongoing toxicological study for micronucleus testing. The present results demonstrate that the new methodology is a valuable tool for improved micronucleus testing. Possible consequences in the field of genetic toxicology are discussed.

Molecular cloning of the S-antigen cDNA from bovine retina

S-antigen is the major component of the soluble proteins in the retina and the pineal, and is thought to play a regulatory role in the visual cycle. It induces experimental autoimmune uveitis(E.A.U.) in various species of laboratory animals. We have cloned the cDNA of S-antigen from bovine retina, containing the entire coding region, and determined its nucleotide sequence. The sequence consists of a 1212 nucleotide region that specifies the amino acid sequence, a 368 nucleotide 5′ untranslated region and a 80 nucleotide 3′ untranslated region. The previously reported partial amino acid sequence defining the carboxy terminal moiety of the polypeptide, fits into our sequence. Homologies were found between the predicted amino acid sequence of S-antigen and that of α transducin.

The role of the chimpanzee in the evaluation of the risk of foreign chemicals to man

Various species of laboratory animals are used to evaluate the efficacy and safety of drugs in man. However, the extrapolation of data from animals to man is often complicated by species differences in the disposition of foreign chemicals. The findings of comparative metabolism studies are used to illustrate species differences in metabolic pathways, rates of biotransformation, kinetics, and excretion routes. Biochemical and structural consequences of the significant differences in enzyme induction between rodents and primate species are discussed. Among the primates, the chimpanzee has been shown to be the most closely related to man not only in the disposition of xenobiotics, but also in the aspects of endocrinology, serology, and immunology. It would, therefore, be the best possible model to predict the fate and effects of foreign chemicals in man. Due to the limited availability of chimpanzees, however, they can only be used for the evaluation of the most critical chemicals and drugs. Comparative metabolism and disposition studies, e.g., of compounds representative of classes of chemicals in chimpanzees and other animals can be used to select suitable species for toxicological testing with larger numbers of animals. Only when the pertinent differences between the selected test species and man are known can correct extrapolations to man be made.

Animal models for feeding Kenyan wild-caught phlebotomine sandflies (Diptera:Phlebotomidae)

Wild-caught phlebotomine sandflies were captured from rock crevices and termite hills and released into feeding cages containing various species of laboratory animals, to find suitable hosts for feeding flies for experimental or breeding purposes. Flies captured from rock crevices did not feed as well as those human-baited at termite hills. The ubiquitous species from the termite hills was Phlebotomus martini, the major vector of kala-azar in the study area (Machakos District of Kenya). This anthropophilic species feeds readily on the mammalian laboratory animals. Cooling flies before feeding stimulated them to feed.

Determination of fibrinolytic activity in the plasma of several animals by means of chromogenic substrate

The chromogenic substrate S-2251 (H-D-Val-Leu-pNA), a high specific and sensitive for SK-plasminogen complex and plasmin in man, was used for determination of plasminogen and anti-plasmin in various species of laboratory animals. Plasma plasminogen of the monkey, dog, rat and rabbit showed significant species differences in activation by the streptokinase; those of the rat and rabbit were not activated by the streptokinase. Therefore the urokinase was better for activation of the plasminogens of these animals. The anti-plasmin activity was highest in the rat, and followed in an order of the monkey, rabbit, man and dog.Using the method for determination of the plasminogen activity established in the above studies, influence of alloxan-induced hyperglycemia on the plasminogen activity in the rat was studied and found that it decreased by the alloxan treatment. No change was observed in the anti-plasmin and plasmin activities.

Attempts to reproduce amyotrophic lateral sclerosis in laboratory animals by inoculation of Schu virus isolated from a patient with apparent amyotrophic lateral sclerosis.

A virus isolated from the CSF of a patient who had amyotrophic lateral sclerosis for 7 years, and prolonged pleocytosis in the CSF, was adapted to suckling mouse brain by subsequent serial blind passages. This Schu virus belongs to the tick-borne encephalitis complex of the genus Flavivirus (Togaviridae). Suckling mouse brain homogenate of the 13th passage was used for transmission experiments in various species of laboratory animals. Golden hamsters infected subcutaneously fell ill after a number of months, lost weight, and had paresis of the legs. Histologically they had petechial hemorrhages in different parts of the CNS and inflammatory changes in the gray substance of the spinal cord. Pilot studies with repeated inoculations of small doses of different flavivirus strains suggest a course of the disease in experimental animals which resembles slow-virus infections insofar as no encephalitis is produced and degenerative changes of the anterior horn cells prevail over inflammatory signs in the spinal cord. After intracerebral application of Schu virus, cynomolgus monkeys developed the typical lesions of togavirus panencephalitis with epileptic seizures, ataxia, and paresis. After subcutaneous application, the virus seems to spread along peripheral nerves to anterior spinal roots and spinal cord, where mainly motor neurons of the anterior horn are damaged, and from there to the brain. The histological findings are such that one may assume the disease of the patient was due to the infection with the virus isolated from his CSF. Therefore, the hypothesis may be advanced that at least some of the cases diagnosed as amyotrophic lateral sclerosis are due to a togavirus infection.

Is the solitary dark neuron a manifestation of postmortem trauma to the brain inadequately fixed by perfusion?

Dark neurons, classified as solitary because of their sparse occurrence, were discerned in the transitional zones between gray and white matter in various species of laboratory animals fixed by perfusion. These neurons, histologically indistinguishable from dark neurons in immersion fixed material, tended to develop when the saline perfusion was delayed or slow, the amount of the Bouin fixative was excessive, or the autopsy was performed shortly after the perfusion. Under these conditions, the white matter manifested a softer consistency and a paler color than the gray matter. These observations suggest that, as the consequence of regional differences in intensity and speed of fixation, distortion during extraction of the brain may activate a stress force in the transitional zones where incompletely fixed neurons become affected and acquire an abnormal affinity for aniline dyes and silver.

Pulmonary aryl hydrocarbon hydroxylase: Tobacco smoke-exposed guinea pigs

Exposure of various species of laboratory animals (rats, hamsters, and mice) to tobacco smoke or tobacco smoke condensate usually results in increased activity of aryl hydrocarbon hydroxylase (AHH) in the lung. In an ongoing study on tobacco smoke toxicity, guinea pigs were exposed to smoke from five regular Canadian flue-cured tobacco cigarettes. The activity of AHH was measured 1, 3, 6, 12, and 24 hr after smoke exposure. Contrary to what has been observed in other species, cigarette smoke did not enhance AHH activity in the guinea pig lung, but rather depressed it. Exposure to the vapor phase of cigarette smoke did not depress AHH activity in the lung, while exposure to whole smoke from nicotine-free cigarettes resulted in a depression of AHH activity similar to that obtained with regular flue-cured tobacco cigarettes. 3-Methylcholanthrene injected ip at 50 mg/kg also failed to induce benzo(a)pyrene hydroxylase in the lung of guinea pigs 18 hr later, and Arochlor 1254 (500 mg/kg, ip) produced even a marked depression of AHH activity. In contrast, benzo(a)pyrene injected ip at 50 mg/kg did induce pulmonary AHH 18 hr later. All three chemicals were inducers of hepatic AHH. Treatment of Sprague-Dawley rats with the same chemicals produced a marked induction of this enzyme in both the lung and the liver. The present study suggests that this species difference in the inducibility of pulmonary AHH will have to be taken into account in future studies on acute and chronic toxicity of tobacco smoke.

Methods for the estimation of acetylcholinesterase activity in the plasma and brain of laboratory animals given carbamates or organophosphorus compounds.

This report describes the modifications necessary to adapt the pH Stat and Ellman methods for the estimation of cholinesterase activity in the plasma and brain of various species of laboratory animals. Both methods were evaluated in studies in which cholinesterase inhibitors, carbamates and organophosphorus compounds, were given to the animals.

Modifications of the michel delta pH method for the estimation of plasma, erythrocyte and brain cholinesterase activities of various species of laboratory animals.

This report describes the modifications necessary to adapt the Michel method for the estimation of cholinesterase activity in the blood and brain of various species of laboratory animals.

Transplacental transmission of antibodies against fraction I of pasteurella pestis to the offspring of experimental animals

Using the reaction of passive hemagglutination, it was possible to follow the dynamics of transplacental transmission of antibodies to fraction I of the plague bacillus by females of various species of laboratory animals. The titers of antibodies received by the young were 4–16 times less than those in their mothers. Passively transmitted antibodies were discovered in the young within 10 to 50 days after birth. Rats aged from 5 to 30 days born of immune females responded to single active immunization by an increase in the titer of corresponding antibodies.

Evaluation of Acetylsalicylic Acid Esterase in Aspirin Metabolism: Interspecies Comparison

The hydrolysis of acetylsalicylic acid in vitro by serum from various species of laboratory animals and humans has been estimated by spectrophotometric measurement of salicylic acid appearance. Various animal species differ widely in their serum aspirin hydrolysis rates, with cats and rabbits approximating the human rate. Rats greatly exceed the rate for man, while dogs show a much slower rate. Human serum samples in vitro show considerable individual differences in acetylsalicylic acid esterase activity. A variety of serum concentrations, temperatures, and buffers have been compared. In vivo aspirin hydrolysis was also compared in 20 humans using an adaptation of the Brodie method, which measured aspirin blood levels at various time intervals following oral administration of buffered and unbuffered aspirins.