Chocolate, an effective means of oral drug delivery in rats
Lab animal, 2002
Oral gavage is an important procedure for drug discovery and efficacy studies using rodents. Howe... more Oral gavage is an important procedure for drug discovery and efficacy studies using rodents. However, there are welfare issues related to the use of the method by inexperienced persons or for long-term studies. The authors describe an effective method of administering drugs to rats by mixing the drug with chocolate to provide a consistent and reliable method of oral drug delivery to large groups of rats for a long period of time.
New Council of Europe regulations mandate housing of two rabbits in the same cage space currently... more New Council of Europe regulations mandate housing of two rabbits in the same cage space currently used to house one, provided the animals are socially compatible. This study was designed to assess changes in growth and selected serum chemistry parameters due to pair housing or single housing of rabbits. Six sets of four female siblings of Crl:KBL(NZW)BR rabbits were used. The animals were seven weeks old on arrival. Two siblings of each set were allocated to pair housing, two to single housing. The animals were housed in stainless steel cages (120 cm × 60 cm × 60 cm) with a perforated floor, including a shelf (60 cm × 30 cm) at 30 cm height from the floor. The rabbits were provided with an aspen cube (5 cm × 5 cm × 5 cm), one item per animal. The rabbits were weighed and blood samples were taken from the auricular central artery at four different times during the study. Blood sera were assayed for a set of routinely assayed clinical chemistry parameters: alanine aminotransferase (AL...
Candida albicans strains with a deletion of the mitogen-activated protein kinase CEK1 gene are de... more Candida albicans strains with a deletion of the mitogen-activated protein kinase CEK1 gene are defective in the yeast to hyphal transition on solid surfaces in vitro. The virulence of a cek1v/cek1v null mutant strain was compared with its wild-type parent strain (WT) in a novel model of localized candidiasis. The mammary glands of lactating mice (at day 5 postpartum) were infected for 2, 4 and 6 days with 50 Wl suspension containing 1U10 S , 1U10 T and 1U10 U blastospores before death. Infected and non-infected control glands were evaluated pathologically. All animals infected with cek1v/cek1v null mutant strains showed no lesions while 65% of animals infected with the WT strain had severe lesions characterized by widespread heterophilic infiltration, necrosis, and abscess formation. As an additional control, animals infected with the disrupted strain complemented with the WT CEK1, on a replicating plasmid, also showed severe pathological changes similar to the WT strain. These results clearly demonstrate that the CEK1 gene codes for a virulence determinant of C. albicans and that the mouse mastitis model is well suited for the discriminative study of the pathogenicity of different C. albicans strains.
The murine model of mycotic mastitis was used to study the efficacy of amphotericin B (AmB). Twen... more The murine model of mycotic mastitis was used to study the efficacy of amphotericin B (AmB). Twenty-four BALB/cJ mice at the fifth day of lactation were anesthetized and inoculated through the teat canal (two glands) with 50 Wl suspension containing 5.0U10 7 cfu ml 31 Candida albicans blastospores. Mice were randomly divided into two groups: untreated controls and AmB treated. Animals were euthanized 3 and 6 days after infection and treatment (4 mg kg 31 per day intraperitoneally). The fungal burden of the mammary gland was determined by quantitative cultures. The number of C. albicans cells recovered from mammary gland homogenates were significantly lower in the AmB treated animals (both 3 and 6 days post-infection) than in the untreated controls (P 6 0.007 and P 6 0.003, respectively). The mammary glands of all untreated control animals showed marked neutrophilic infiltration, severe necrosis, and presence of blastospores, hyphae and pseudohyphae. In contrast, 10 of 12 animals treated with AmB showed only a mild neutrophilic infiltration which was restricted to alveoli and excretory ducts. All extra-mammary organs were free of infection in both groups. The results demonstrate that the murine mycotic mastitis model is suitable for investigations of new antifungal compounds. In addition, this model is more lenient than the systemic candidiasis models.
Reduced pathogenicity of a Candida albicans MAP kinase phosphatase (CPP1) mutant in the murine mastitis model
APMIS, 1998
Candida albicans strains with a deletion of the mitogen‐activated protein kinase tyrosine phospha... more Candida albicans strains with a deletion of the mitogen‐activated protein kinase tyrosine phosphatase gene (CPP1) are derepressed in the yeast‐to‐hyphal transition on solid surfaces in vitro at ambient temperatures and this gene is therefore required for repression of the yeast‐to‐hyphal switch. The pathology caused by a CPP1 null mutant strain was compared with that of the null mutant into which the wild‐type CPP1 gene was introduced by homologous recombination and with the wild‐type parent strain in a murine mycotic mastitis model. The mammary glands of lactating mice (at day 5 postpartum) were infected for 2, 4 and 6 days with 1 times 105, 1 times 106 and 1 times 107 cell‐forming units before euthanasia. Infected and non‐infected control glands were evaluated histopathologically. The null mutant strains showed less severe pathology than the two control strains. The Cpp1p tyrosine phosphatase may thus be considered a virulence determinant during localized infection in C. albicans.
Development and validation of a localized murine candidiasis model. PhD thesis
A murine model of localized candidiasis (mastitis) was developed. The model was analyzed withresp... more A murine model of localized candidiasis (mastitis) was developed. The model was analyzed withrespect to its discriminative abilities through investigation of the virulence properties of C.albicans mutant strains compared with the wild-type parental strain. Further validation of themodel was undertaken by assessment of pathogenesis, chemotherapy (amphotericin B andfluconazole) and complement activation using immunocompetent BALB/c mice, SCID andathymic nude mice. Six to eight week old mice were time mated. The pups were allowed to suckleup to day five post partum, at which time the lactating glands were inoculated with between 104 to109 cells of Candida. The animals were euthanized after 1-6 days of infection. The mammaryglands and several other organs were evaluated histopathologically. In the chemotherapy studies,the mammary glands were homogenized and fungal burden determined through culture of differentdilutions of the homogenate. Except in the very high inocula dose, the fungi were confined to themammary gland tissues. The infection remained localized and was most severe in SCID, followedby immunocompetent and athymic nude mice, in that order. The severity of pathological changes,which consisted of infiltration with neutrophils, necrosis and abscess formation, was exacerbatedby increasing the number of cells and/or the duration of infection in the untreated control animals.Animals infected with virulence factor knock-out strains showed reduced or no lesions while themajority of the animals infected with the wild-type strains showed severe lesions. In theamphotericin B treated animals, only mild pathological changes were seen compared to theinfected controls. Fluconazole treatment was ineffective in the treatment of mastitis. Complementfactor C3c levels were elevated and correlated to the severity of inflammation in all theexperiments and were significantly reduced by amphotericin B but not by fluconazole treatment.Conclusions: i) the murine mycotic mastitis is a discriminative model of localized candidiasis ii)severity of infection is dose- and duration-dependent iii) antifungal drugs can significantly reducefungal burden in the mammary gland and iv) there are other immune mechanisms that protect miceagainst dissemination of infection than T and B cell immunity.
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