Experimental Infection Of Rats Research Articles

Ovarian development of Corynosoma semerme (Acanthocephala) during experimental infections in rats.

The general structure and aspects of the development of the ovaries of the palaeacanthocephalan Corynosoma semerme were studied by transmission electron microscopy using worms varying in age from 18 to 90 h obtained from experimental primary infections in hydrocortisone-treated rats instead of seals, which serve as the natural definitive hosts. The observations can be interpreted to show that the immature ovaries become transformed relatively rapidly from cellular spheres to the more complex mature ovaries consisting of the supporting and oogonial syncytia and the germ-line cells. The supporting syncytium developed before the oogonial syncytium. The cytological appearance of ovaries from worms from rats was found to be similar to that of ovaries from mature worms of unknown age from naturally infected seals. Ecological evidence is considered to suggest that the rapid maturation of C. semerme in rats may also occur when the parasite becomes established in seals.

Development of the Ovary and the Female Reproductive Cells of the Lung Fluke, Paragonimus ohirai (Trematoda: Troglotrematidae)

The ultrastructure of the ovary of Paragonimus ohirai was investigated in different developmental stages of experimental infection in rats, from the metacercarial stage to the adult stage. The female reproductive cells were observed in order to understand the development of the ovary. During its development in the definitive host, the ovarian primordium and the ovary increased in size and cell number and underwent morphological changes. The blind end of the female genitalia was an undifferentiated primordium at the metacercarial stage, but became the bud of an ovary on day 3. Germ cells and supporting cells were observed on day 5. Oogonia were identified in the 15-day-old ovary, followed by the appearance of young oocytes at 17 days. Large oocytes were found on day 19, but the 21-day-old ovary contained degenerated oocytes. Mature ovaries were observed in the 26-day-old worms and egg formation was seen to arise on day 28. The development of the ovary and female reproductive cells was discussed in relation to the physiology of P. ohirai.

Activity of teicoplanin in localized experimental infections in rats

We tested the ability of teicoplanin alone and in combination with rifampicin or gentamicin to cure experimental endocarditis and granuloma pouch infections in rats caused by Streptococcus faecalis, Str. sanguis, methicillin-sensitive and -resistant Staphylococcus aureus. Vancomycin and ampicillin were also tested. Teicoplanin was more active than vancomycin and ampicillin. Combinations of teicoplanin with rifampicin or gentamicin were significantly more effective than single drug therapy. These results suggest that teicoplanin could be an interesting alternative to vancomycin in the treatment of serious streptococcal and staphylococcal infections in man.

Trickle infections of Nippostrongylus brasiliensis in rats.

Much of our knowledge of immune responses to gastrointestinal nematode infections stems from study of the rat/NippostrongyIus brasiliensis system. Most experimental infections of rats with N. brasiliensis consist of a single inoculation of many larvae resulting in the establishment of a worm population that is usually almost completely expelled within 2 weeks, leaving the host strongly resistant to challenge infections (Ogilvie and Jones 1971, Exp Parasitol 29:138-177). It has often been suggested that repeated inoculation with small numbers of larvae, called trickle infections, may more closely resemble naturally occurring infections. Despite the importance of this suggestion for the interpretation and understanding of immune and pathological processes during helminth infections, experimental investigation of the kinetics of trickle infections of N. brasiliensis is limited mainly to the work of Jenkins and Phillipson (Jenkins and Phillipson 1970, Parasitology 62:457-465; 1972a, Int J Parasitol 2:105-111; 1972b, Int J Parasitol 2:353-359; Jenkins 1972, Parasitology 65:547-550; 1973, Z Parasitenkd 41:73-82; 1974, Parasitology 68:13-17). They found that when rats were given a small number of larvae 5 times a week for 4-16 weeks, the worms which became established in the intestine persisted and continued egg production for many months. Following such trickle infections they recorded mean worm burdens of 150-250 or percentage takes of 50%-60%, which is the same as the percentage take at the peak of a primary infection (Ogilvie and Jones 1971, Exp Parasitol 29:138-177). On the basis of these results it is generally accepted that when infections of N. brasiliensis are acquired gradually, immune expulsion is impaired and a population of adapted worms continues producing eggs for several months. The present report describes two more experiments in which worm burdens and egg production were measured following trickle infections of N. brasiliensis. The rats used were of the same strain and sex as those routinely used by Jenkins and Phillipson. Outbred male Sprague-Dawley rats (purchased from Bantin and Kingman Ltd., UK) were housed in groups on sawdust, kept at about 18 ~ C with natural lighting and given food (Oxoid 41B, Herbert Styles Ltd., UK) and water ad lib. The methods of larval

Altered hepatic microsomal drug-metabolizing enzyme activity resulting from experimental infection of rats with Trypanosoma b. brucei.

Infection of experimental rats with Trypanosoma brucei (T. b. brucei) results in a decrease in the activities of aniline hydroxylase, aminopyrine-N-demethylase and a lowering of the level of reduced glutathione in the liver. The activity of cytochrome c reductase remains above normal 50 h after infection. Infection of animals previously treated with either phenobarbitone or 3-methylcholanthrene results in a reduction in the specific activity of aniline hydroxylase and aminopyrine-N-demethylase. However, the specific activity of aromatic hydrocarbon hydroxylase is not depressed in 3-methylcholanthrene-treated rats.

Incorporation of [14C]-leucine into complement in experimental infection of rats in malnourished stages

The complement biosynthesis was examined in the first complement response, that is at the stage of elevated complement level 3 days after Staphylococcus aureus infection, since this elevation might play a role in host defence before antibody response. [14C]-leucine was used as a labeled amino acid to examine the de novo synthesis of the complement. In the first complement response, the malnourished rats red with 0.5% protein, both in infection and noninfection groups, showed a significantly higher specificity in newly synthesized complement activity than did the rats in the well-nourished group fed with 18% protein. The infected rats showed much higher rates of de novo synthesis of complement activity than noninfected rats and this effect was more predominant in the malnourished group.

Secondary infection of rat lungs with Pasteurella pneumotropica after Kilham rat virus infection.

Lung congestion was observed after an outbreak of Kilham rat virus infection (KRV) in a rat colony, previously free of all rat viruses. A high proportion of congested lungs contained Pasteurella pneumotropica suggesting that KRV might have caused primary damage to the alveoli (hitherto not recorded) which allowed the secondary bacterial colonization. Experimental infection of rats with KRV caused acute damage to the lung alveoli. Since KRV infection is very common in animal facilities it could therefore be a significant agent in the development of respiratory disease.

Production of bladder stones by human T mycoplasmas.

SINCE the first isolation of human T mycoplasmas1, their pathogenic role has remained controversial. These organisms, present in the urogenital tract of men and women, are unique among mycoplasmas in possessing urease2. They have recently been isolated from other mammals3–5. Bovine strains have caused experimental pneumonitis in calves6 and mastitis in cattle. In the latter experiment, human T mycoplasmas were unable to produce mastitis7. Human T mycoplasmas have been implicated as causative agents of non-gonococcal urethritis in men and pelvic inflammatory disease, puerperal infection and reproductive failure in women8. Their true relationship to human disease, however, remains unknown, and until now they have never been reported to produce disease in experimental animals. We now report the production of bladder stones during experimental infection of rats by human T mycoplasmas.

THE KILLIFISH, FUNDULUS HETEROCLITUS, SECOND INTERMEDIATE HOST OF THE TREMATODE, ASCOCOTYLE (PHAGICOLA) DIMINUTA

The metacercarial stage of Ascocotyle (Phagicola) diminuta Stunkard and Haviland, 1924 has been found encysted in the gills of Fundulus heteroclitus. Experimental infections of rats, mice, hamsters, Larus argentatus and Nycticorax nycticorax have yielded adult worms and permitted additions and emendations to the description of the parasite.

Serologic Response of White Rats to Toxoplasma Infection

In an earlier paper from this laboratory, it was reported that about 20 per cent of the wild Norway rats of Memphis gave positive tests for toxoplasmosis using the Sabin-Feldman dye test. Only about three per cent of the same group of rats could be shown to harbor parasites which could be recovered after the inoculation of brain tissue into susceptible mice or guinea pigs (Eyles, 1952). In the discussion of that paper, it was pointed out that experimental infections in rats would have to be studied before the significance of the positive serologic reactions could be interpreted. The present paper reports serologic findings using the Sabin-Feldman test from albino Norway rats with experimentally induced Toxoplasma infections.

The Experimental Infection of Rats withEntamoeba Histolytica; with a Method for Evaluating the Anti-Amoebic Properties of New Compounds

(1946). The Experimental Infection of Rats with Entamoeba Histolytica; with a Method for Evaluating the Anti-Amoebic Properties of New Compounds. Annals of Tropical Medicine & Parasitology: Vol. 40, No. 2, pp. 130-140.

Experimental Infection of Rats with the Balantidium from the Pig

Experimental Infection of Rats with the Balantidium from the Pig

Experimental infection of rats and mice with the common intestinal Amoebae of man

Experimental infection of rats and mice with the common intestinal Amoebae of man