Different Organs Of Mice Research Articles

Experimental infection of pups with Ancylostoma caninum-infected mouse tissues

Migration and distribution of Ancylostoma caninum larvae in the tissues of mice orally infected with 1000 larvae, and establishment of patent infection from the mice to the definitive host, were studied. Larval yield from different organs of mice, after digestion with artificial gastric juice, indicated that the highest recovery was at 4 h post-infection (62.8%), and thereafter a slight decline occurred up until 30 days post-infection (51.5%). Migration of larvae to the lungs occurred within 4 h, to the liver within 12 h and into the heart within 24 h. No larvae were recovered from spleen and kidney tissues. From the 9th day onwards larvae were also recovered from the brain. Migration in the muscles of head and neck occurred within 4 h, in the thoracic and abdominal muscles at 24 h and in lumbosacral and leg muscles at 48 h. The establishment of patent infections in the definitive host was studied by feeding the orally- and percutaneously-infected mice to hookworm-free pups at 10 and 30 days post-infection. The mean necropsy worm burden in the pups fed with the orally-infected mice was comparatively higher than in the pups fed cutaneously-infected mice.

Continuous production of interferon in normal mice: effect of anti-interferon globulin, sex, age, strain and environment on the levels of 2-5A synthetase and p67K kinase.

Two interferon-mediated enzymes, a 2-5A synthetase and a kinase that phosphorylates a 67 000 mol. wt. (p67K) protein were found at variable levels in different organs of mice. Among the different strains of mice included in this study, germ-free mice had the lowest levels of these enzymes. The levels of 2-5A synthetase and p67K kinase were enhanced significantly in all mice following treatment with mouse (alpha + beta) interferon. Here, we show that the presence of 2-5A synthetase and p67K kinase in different organs of normal mice (untreated) was due, at least in part, to a constant production of interferon under different physiological conditions. Accordingly, injection of normal mice with anti-mouse interferon (alpha + beta) globulin led to a significant decrease in the level of 2-5A synthetase and p67K kinase. In conventional mice (C3H/He), the level of both of these enzymes was higher in female than in male animals and was decreased with age or when such animals were reared isolated in a pathogen-free protected unit. The levels of 2-5A synthetase and p67K kinase were also decreased in normal mice following injection with a powerful antibiotic against a very wide spectrum of Gram-positive and Gram-negative bacteria. These results suggest that the production of interferon was induced continuously in normal mice. Such induction was mediated by both internal and external agents.

Production and action of interferon in mice infected with rabies virus

Summary This study describes the production and action of interferon in mice infected with rabies virus (challenge virus strain). The production of interferon was monitored by an in vitro assay of plasma and extract of spleen, lung and brain for interferon activity. The action of interferon in mice was assessed by measuring two interferon-mediated enzyme activities, 2–5A synthetase and poly(I)poly(C)-Sepharose-bound protein kinase. Mice (strain C3H/He) infected with rabies virus were sacrificed at different time intervals, and the level of both enzyme activities was measured in extracts of spleen, lung and brain. Inoculation of mice with a mouse brain homogenate containing rabies virus resulted in the production of interferon with two different peaks detectable in the plasma: an early peak 24–48 h after inoculation followed by another peak on the sixth day of infection. The first peak was found to be independent of rabies virus, since it was also detectable in control mice injected with a brain homogenate from a normal uninfected mouse. The second peak of interferon, however, was probably due to the presence of high levels of interferon in the brain in response to rabies virus replication. In accord with the production of interferon, the level of 2–5A synthetase and protein kinase was enhanced several-fold in the different organs of mice infected with rabies virus. The level of protein kinase activity in the brain was strikingly higher than that of the spleen or the lung of mice 4 days after infection, and this level remained elevated until the death of the animals. These results indicate that infection of mice with rabies virus results in the production of interferon which is active in the infected mice, since different organs respond to it by elevated levels of 2–5A synthetase and protein kinase. Interferon produced during rabies virus infection, however, seems to be ineffective in inhibiting replication of virus, since these mice do not survive.

A practical procedure for testing DNA damage in vivo, proposed for a pre-screening of chemical carcinogens

The alkaline elution method was adapted to the evaluation of DNA damage induced in vivo through a practical and reliable microfluorometric procedure, without any need for tissue pre-labeling. The DNA damage induced in vivo by treatment with a single dose of N-nitrosodimethylamine (DMNA), N-methyl- N-nitroso-urea (MNU), 1,2-dimethylhydrazine (DMH) or cycasin has been detected in different organs of mice or rats. The results obtained are rather consistent with the organotropism of these carcinogens, and show a satisfactory dose dependence of DNA damage. DMH and cycasin, both negative in the Ames' Salmonella/microsome mutagenicity test, are clearly positive with in vivo DNA damage/alkaline elution assay. This latter method, complemented with other short-term tests, may play a useful role in the pre-screeing of chemical carcinogens.

Metabolism of deoxycytidine in different organs of mice and rats.

Metabolism of deoxycytidine in different organs of mice and rats.

Metabolism of labeled nicotinamide coenzyme in different organs of mice and rats.

SummaryReplacement of radioactive NAD in different organs of rats and mice was found to be most rapid in kidney, liver, and intestine and slowest in brain, muscle, and testis. Experiments with nicotinamide as precursor indicate that nicotinamide derived from NAD degradation is extensively reutilized in the latter organs. Injection of labeled nicotinamide together with a large amount of cold nicotinic acid suggests that this reutilization in brain and muscle probably does not involve deamidation of nicotinamide to nicotinic acid.