Outbred Albino Mice Research Articles

Schistosoma mansoni: aspectos quantitativos da fertilidade e sobrevida de vermes oriundos de cercárias irradiadas com 3 Krad, em camundongos

The effect of gamma irradiation on the fertility of female mice, as well as the survival of worms in their portal system, have been observed in four groups of outbred albino mice (Mus musculus), experimentally infected with ca 450 cercariae of Schistosoma mansoni (LE and SJ strains), by transcutaneous route. The cercariae used were a) non-irradiated (control groups), and b) irradiated with 3 Krad of gamma irradiation (Co-60). From the 33rd day on, some stability in the population of surviving worm could be observed. This population remained constant till the end of the observation period (90th day), notedly in relation to the LE strain. Thus, it was concluded that gamma irradiation (at the dose of 3 Krad) is able to hinder the worm egg production in 98.1% of the infected mice. Further, it was observed that the few detected eggs were dead. Females were found to be more resistant to irradiation. The irradiation effect on the mortality of male worms was statistically significant scarcely from the 61st day on. The long period of permanence of the sterile adult irradiated worms in the portal system of mice and their probable involvement in the development of immunoprotection (the so-called concomitant immunity, without the immunopathological involvements for the host) are here discussed.

Schistosoma mansoni: evolução de vermes oriundos de cercárias irradiadas a nível de sistema porta, no camundongo

Eight groups of outbred albino mice were infected transcutaneously with cercariae of S. mansoni (strains LE and SJ) irradiated with either 3, 20 or 40 Krad, of gamma radiation from a cobalt-60 bomb and a control non irradiated group. Cercariae irradiated with 20 or 40 Krad failed to develop in the portal system and 3 Krad retarded development. Worms of the SJ strain developed more slowly than the LE strain.

Effects of betamethasone on the course of experimental infection with Trypanosoma cruzi.

In this experiment, the effect of betamethasone administered in the early post- acute infection of mice by Trypanosoma cruzi was studied. This drug was administered during 30 days after the 42nd day of infection in a dose of 0.15 mg/day. The betamethasone treatment did not cause fresh outbreaks of parasitemia and the histopathological findings in the chronic phase were not different from those in the control group. The higher cumulative mortality after treatment in the experimental group was due to superimposed bacterial infections. Outbred albino mice infected with low numbers ofY strain Trypanosoma cruzi trypomastigotes were not suitable models for Chagas' disease, since after 7 months of observation only mild histological lesions developed in all the animais. Prolonged betamethasone treatment of mice infected with low numbers o/Trypanosoma cruzi of the Y strain, during the post-acute phase did not aggravate the course of infection.

Micronuclei and other nuclear anomalies induced in various organs by diethylnitrosamine and 7,12-dimethylbenz[ a]anthracene

(Accepted 11 February 1986) A large number of carcinogens have been assayed for genotoxic activity in the rodent bone marrow micronucleus test (Heddle et al., 1983). However, the test appears to lack sensitivity towards a number of carcinogens. One reason for this insensitivity may be that the bone marrow is not a target organ for these carcinogens and thus there is a distinct need to monitor genotoxic effects in additional organs or tissues of the treated animal (Ashby, 1983). Genotoxic agents are capable of causing a variety of cell nucleus changes such as pyknosis, karyorrhexis, aptosis as well as micronuclei (Matter and Schmid, 1970; Wargovich et al., 1983) and recently it has been shown that some carcinogens, which have little or no effect on the bone marrow, are capable of causing micronuclei and nuclear anomalies in the cells of other organs (Tates et al., 1980; Goldberg et al., 1983; Ronen et al., 1983). In this study we have examined the ability of diethylnitrosamine (DEN) and 7,12-dimethyl- benz[a]anthracene (DMBA) to induce nuclear anomalies in the urinary bladder, colon, liver and lung of weanling mice and have compared this with micronucleus formation in polychromatic erythrocytes of the bone marrow of the same animals 24 h after administration. It was found that DMBA induced nuclear anomalies in the bone marrow and colon while DEN induced anomalies in the bladder, colon, liver and lung but not the bone marrow. Materials and methods Weanling (21 days old, weighing 12 g) Swiss Crl: CD ® -1 (ICR) BR outbred albino mice were ob- tained from Charles River UK Ltd. Weanling mice were chosen because they have been reported to be more susceptible to tumour induction by a variety of chemicals (Vesselinovitch et al., 1979), and also the expected higher numbers of dividing cells in the somatic tissues would possibly enhance their sen- sitivity to genotoxins. The animals were allowed tap water and standard laboratory diet throughout the experiment. DEN (CAS registry 55-18-5, pfs grade) and DMBA (CAS registry 53-97-6, approx. 950-/0 pure) were obtained from Sigma. DEN was dissolved and DMBA was suspended in the vehicle, aqueous 1 °70 methylcellulose just prior to administration by oral gavage in a dosage volume of 20 ml per kg bodyweight. The dose levels used were chosen on the basis of a small preliminary acute toxicity test and were approximately the maximum tolerated dose (MTD/24 h). The animals were dosed when 21 days old and sacrificed 24 h later. 5 male and 5 female mice were selected at random from the surviving animals in each group (some mortalities occurred in the DEN- treated group). 5 male and 5 female mice treated with the vehicle alone formed a control group. Bone marrow smears were made from the selected animals and stained with Giemsa. All 0165-7992/86/$ 03.50 © 1986 Elsevier Science Publishers B.V. (Biomedical Division)

Tissue eosinophilia and Leishmania mexicana mexicana eosinophil interactions in murine cutaneous leishmaniasis

Outbred albino mice were infected subcutaneously with 10(6) amastigotes of Leishmania mexicana mexicana and the subsequent lesions were evaluated by light and electron microscopy at various intervals after infection. The animals developed persistent nodules and a spectrum of lesions of variable size which was correlated with the host's ability to control the parasite in the tissue. During the acute phase of the disease the histopathological results showed an accumulation of granulocytes, some mononuclear phagocytes and a predominance of eosinophils as compared to other cell types. In this early acute phase, eosinophils were found in the tissue together with normal and degranulating mast cells. In the granulomatous inflammatory reaction of the chronic phases, there was infiltration of granulocytes parallel to parasite multiplication and the formation of parasitized vacuolated macrophages. The number of eosinophils was consistently greater than neutrophils, regardless of lesion type or number of parasites present in the tissue. During the acute reaction, the granulocytes apparently destroyed many parasites; however, there was an unvaryingly low level of phagocytosis of amastigotes during the chronic stages by both eosinophils and neutrophils. Neutrophils seemed to be more effective than eosinophils in the killing of ingested parasites. A close association between eosinophils and parasitized macrophages was seen in the chronic lesions; thus, eosinophils might contribute to parasite destruction through co-operation with macrophages.

Inheritance of post‐vaccinal resistance against Plasmodium berghei infection in mice

The protective effect of specific vaccination against Plasmodium berghei (P. berghei) was compared in terms of survival percentage in DBA/2, C3H, outbred albino mice and in two lines of mice produced by selective breeding for either high or low antibody responsiveness to sheep erythrocyte (H and L lines respectively). The efficacy of induced protection varies according to genetic constitution. It is very strong in H line and albino mice, intermediate in DBA/2 and very weak in L line and C3H. The inheritance of post-vaccinal resistance to infection was studied in F1 hybrids and backcrosses between C3H and the other lines. The control was polygenic in all cases. The dominance of the characteristic depends on the strain combination. On the whole the results suggest the non-identity of the genes controlling protection in the various lines. The lack of a quantitative parameter for a more precise genetic analysis of protective immunity in inbred lines is stressed, since both anti-P. berghei antibody production and parasitaemia proved to be unreliable.

Antibody to group B Streptococcus type III in human sera measured by a mouse protection test.

Antibody to group B Streptococcus type III (GBS-III) was measured in human plasma and sera by using a test which measures the ability to protect outbred albino mice from an intraperitoneal challenge of GBS-III calculated to be lethal to 90% of the mice (LD90 dose). Of three samples from three different lots of commercial human immune serum globulin, none were protective despite the presence of antibody to the native type III polysaccharide. Nine specimens were tested from recipients of multivalent pneumococcal vaccine, and none were protective. Five specimens were tested from recipients of GBS-III polysaccharide vaccines who had responded with greater than 50 micrograms of specific antibody per ml in the blood. All of these were protective and could be diluted to titers of 1:10 to 1:40. Of two prevaccination sera with low levels of specific antibody, neither was protective. An unexpected finding which may limit the sensitivity of the mouse protection assay was that the human immune serum globulin and human serum with a very low level of antibody appeared to increase the lethality of the GBS-III test strain, resulting in LD50 values reduced to 0.01 of the usual LD50.

Dopaminergic involvement in attention a novel animal model

1. 1. Adult male outbred albino mice were acutely injected with either of two dopamine (DA) agonists; Apomorphine, a receptor agonist, or Amantadine, a DA releasing agent. 2. 2. Both drugs produced dose-related alterations in initial Y-maze behavior, consisting of significantly increased proportions of 2-arm entries. 3. 3. This behavior has previously been shown to reflect an abnormal attentional process. 4. 4. Thus DA activation may cause sensory perseveration. 5. 5. The implications of this finding for DA theories of psychopathology is discussed.

Influence of formaldehyde and Sonacide (potentiated acid glutaraldehyde) on embryo and fetal development in mice.

Pregnant outbred albino mice were given formaldehyde or Sonacide (potentiated acid glutaraldehyde) by gavage on days 6--15 of gestation. The mice were killed on day 18, the general health and reproductive status of the dam evaluated, and the fetuses examined and processed in order to characterize external, visceral, and skeletal malformations. Although formaldehyde (stock solution containing 12--15% methanol as a preservative) was lethal to 22 of 34 dams treated with 185 mg/kg/day, and one of 35 dams treated with 148 mg/kg/day, these doses did not produce statistically significant (two-sided p < 0.05 versus controls) teratogenic effects in the fetuses of the surviving dams. Sonacide was also judged not to be teratogenic to the mice employed in this study, in spite of the fact that relatively high doses were employed. The highest doses of Sonacide studied (5.0 ml/kg/day, which is equivalent to 100 mg/kg/day of glutaraldehyde) killed 19 of 35 dams and caused a significant reduction in the mean weight gain of the surviving mothers. In addition, this dose produced a significant increase in the number of stunted fetuses.

Influence of N-Hexane on Embryo and Fetal Development in Mice

Pregnant outbred albino mice (CD-1) received n-hexane once daily by gavage at doses up to 2.20 g/kg/day on days 6–15 of gestation. Other pregnant mice received higher hexane doses (up to 9.90 g/kg/day), employing a three times a day injection schedule. At the lower, once-daily doses only one dam died and no teratogenic effects occurred. Higher hexane doses (t.i.d.) were toxic: 2 of 25 dams treated with 2.83 g/kg/day, 3 of 34 treated with 7.92 g/kg/day and 5 of 33 treated with 9.90 g/kg/day died. At the 7.92 and 9.90 g/kg/day doses, the average fetal weight was significantly (p<0.05) reduced, but the incidence of malformations in treated and vehicle (cottonseed oil) control groups did not differ significantly. Thus, n-hexane was not teratogenic even at doses toxic to the dam.

Influence of n-hexane on embryo and fetal development in mice.

Pregnant outbred albino mice (CD-1) received n-hexane once daily be gavage at doses up to 2.20 g/kg/day on days 6-15 of gestation. Other pregnant mice received higher hexane doses (up to 9.90 g/kg/day), employing a three times a day injection schedule. At the lower, once-daily doses only one dam died and no teratogenic effects occurred. Higher hexane doses (t.i.d.) were toxic: 2 of 25 dams treated with 2.83 g/kg/day, 3 of 34 treated with 7.92 g/kg/day and 5 of 33 treated with 9.90 g/kg/day died. At the 7.92 and 9.90 g/kg/day doses, the average fetal weight was significantly (p less than 0.05) reduced, but the incidence of malformations in treated and vehicle (cotton-seed oil) control groups did not differ significantly. Thus, n-hexane was not teratogenic even at doses toxic to the dam.

Mouse protection test for group B Streptococcus type III.

The mouse model has been used previously for the study of protection against challenge with strains of group B Streptococcus types Ia, Ib, and Ic, but investigators have not yet been successful in causing lethal disease when type III strains are inoculated. In this study, six clinical isolates belonging to serotype III were lethal in seven-week-old outbred albino mice; the 50% lethal dose (LD50) for mice tested ranged from 1.8 x 10(4) to 4.6 x 10(6). In contrast, a laboratory prototype strain of serotype III was not lethal. The lethality observed with this protection test depended on both the volume of the inoculum given and the medium in which the streptococci were suspended. LD50 values decreased as the volume of the inoculum, given intraperitoneally, increased, up to a volume of 1.5 ml. Hyperimmune rabbit antiserum to a clinical isolate of type III protected mice against an estimated 90% lethal dose of the isolate. Normal rabbit serum and heterologous antisera, except for one of two antisera to type Ia organisms, were not protective. Absorption of type III antiserum with whole organisms of serotype III or with purified, type III-specific polysaccharide inhibited protection of mice against type III organisms.

A Model in Mice for Experimental Leishmaniasis with a West African Strain of Leishmania Tropica *

Outbred albino mice infected on the nose and in one foot pad were used as a model for the study of a newly isolated strain of Leishmania tropica from West Africa. The development of local lesions following the inoculation of 107, 105, and 103 amastigotes, respectively, was recorded at weekly intervals through four subsequent animal passages. In addition, the course of infection was followed in four different inbred strains of mice. The specificity and possible spread of infection were checked microscopically by smear preparations and by inoculation of tissue material into NNN medium. Samples for histopathological examination were obtained at different time intervals after the day of infection. The incubation period varied from 2–7 weeks depending upon the size of inoculum. Generally, the mice developed local swelling and, frequently, ulceration at the sites of inoculation. After a few weeks of progress, the lesions assumed a more chronic state, lasting for months without obvious impact on the general health of the mouse. However, the individual response to the infection varied considerably within each group. Histopathologically, parasitized macrophages and polymorphonuclear leucocytes dominated during the first weeks, whereas at later stages of the lesions lymphocytes and plasma cells prevailed. The BALB/c mice differed from the other mouse strains under study by developing a progressive, ultimately fatal infection. Splenomegaly was prominent in the BALB/c mice, whereas clinical signs of generalized infection were missing in the other mouse strains. However, the latter strains also harbored leishmanial parasites in internal organs, as demonstrable by NNN-culture. The study underlines the value of mice for experimental investigations on L. tropica.

Mouse Model For Protoporphyria I. The Liver and Hepatic Protoporphyrin Crystals

Outbred albino mice were rendered protoporphyric by a diet containing 2.5% (weight) of griseofulvin. There was a 5-fold increase in liver weight, hepatocellular degeneration and necrosis, cholestasis, ductular proliferation and cirrhosis. Liver protoporphyrin values were elevated and brown pigment granules were present in hepatocytes, Kupffer cells, and bile ducts. The granules showed red fluorescence, birefringence, and, at the ultrastructural level, consisted of aggregates of needle-like crystals. Crystals isolated from such livers showed solubility and absorption characteristics of protoporphyrin; in vitro recrystallization of protoporphyrin, extracted from protoporphyric mouse livers, yielded crystals identical with those observed in vivo, and commercial protoporphyrin exhibited similar morphologic features. The liver pathology and protoporphyrin crystals observed in these animals are identical to the liver pathology and crystals observed in the human disease, erythropoietic protoporphyria. In this mouse model, protoporphyrin crystals are intimately associated with hepatocellular injury and it appears that their accumulation within hepatocytes leads to hepatocellular destruction. A similar pathogenesis is postulated for the hepatic damage that occurs in some cases of erythropoietic protoporphyria.

EXPERIMENTAL MURINE LEPROSY:

To propagate bacilli, a suspension of Mycobacterium lepraemurium (MLM) was injected intravenously into 40 outbred albino mice. Pronounced differences were observed in the rate of progression of the infection, and 8 mice representing the clinically observed extremes were histologically examined. Poor clinical condition was found to correlate with the presence of many granulomas and few or no surrounding lymphocytes, indicating weak or absent cell mediated immunity (CMI). Good clinical condition correlated with smaller and fewer granulomas with less bacilli and a pronounced infiltration of small lymphocytes. These observations strongly suggest that outbred mice differ in their susceptibility to MLM‐infection. The basis for this heterogeneity, which bears some resemblance to the spectrum in human leprosy, is assumed to be the varying capacity of individual mice to mount a cell mediated immune response against the mycobacterium.