Oral treatment with ketoconazole in systemic candidosis of guinea-pigs: microbiology, hematology and histopathology

Non-pretreated Albino guinea-pigs were infected intravenously with Candida albicans and treated orally either with placebo or ketoconazole. The 17-day follow-up of the fungal dissemination was based upon hematology, on gross and microscopic lesions and on the demonstration of the fungus by culture techniques. The efficacy of ketoconazole, both with regard to the quantity and the morphology of fungi in various organs and the tissue-healing process are discussed. The treatment of human systemic candidosis will also be considered. No side-effects due to the therapy were observed in these experiments.     

Diagnosis of systemic or visceral candidosis.

Although systemic or visceral candidosis can be diagnosed during life, it is usually discovered at autopsy. Early diagnosis is important since treatment with specific antifungal drugs is effective. The diagnosis should rest on all available clinical and laboratory evidence. Mucocutaneous lesions and chorioretinitis are important clinical findings in the presence of predisposing illness and iatrogenic factors. Repeatedly positive blood cultures for Candida in the absence of an indwelling intravenous line and Candida colony counts of 10 000/ml or greater in urine freshly obtained by catheter in the absence of an indwelling Foley catheter are very significant. Similarly significant is recovery of Candida from closed spaces (pleural, peritoneal, joint or subarachnoid). The agar gel diffusion test for Candida antibodies has a sensitivity and specificity of 85% or greater and can confirm the diagnosis in otherwise doubtful cases. The various antibody tests for Candida are not suitable for random screening because of the low prevalence of visceral or systemic candidosis in the general population.     

Histopathology of experimental Aspergillus fumigatus keratitis

Histopathological studies in rabbit's eyes, 7 and 14 days after intracorneal inoculation with 1×10⁵ Aspergillus fumigatus conidia have been performed.Similar lesions were found in both periods with fungal hyphae in the anterior third of corneal stroma, round cell infiltration from the sclero-corneal edge and in the anterior chamber and, neovascularization.No lesions were found in the Descemet's membrane.Gomori silver-methenamine stain with hematoxiline-eosine counter-stain was found to be the most reliable stain to detect fungal presence in corneal stroma, and Masson's trichromic stain in the study of pathological changes in ocular elements.     

Histopathology of experimental scuticociliatosis in turbot Scophthalmus maximus

A scuticociliate strain (B-2), originally isolated from an outbreak in a turbot Scophthalmus maximus (= Psetta maxima) farm in Galicia (northwestern Spain) and maintained in axenic culture, was injected intracoelomically (lethal dose 80 equivalent, LD80) in healthy turbot (50 g). Ciliate-injected fish were kept under controlled conditions in a recirculating seawater system and sampled on Days 1 through 8, 10, 12 and 14 postinfection (PI). Necropsies were conducted and included blood collection from the caudal vein and samples of liver, spleen, heart, digestive tract, kidney, gills, abdominal wall and neurocranium taken for routine histology. Mortality occurred from Day 6 until Day 12 PI and reached 66.7% by the end of the experiment. Presence of ciliates in the coelomic fluid was scarce until Day 4 PI. Parasitaemia was only observed from Day 5 until Day 10 PI and its incidence was always low. Presence of scuticociliates in tissue sections followed a progressive pattern of diffusion, with ciliates showing preference for loose connective tissue and also a clear haematophagous activity. The most severely affected organs were the pancreas and digestive tract. No special tropism for nervous tissues was observed in this study. The inflammatory reaction was variable depending on the tissue. After 3 wk, survivors had apparently managed to extinguish the infection.     

Histopathology of the dentomaxillary system in experimental fluorosis]

Dynamics of experimental dental fluorosis and regress of the process were studied on albino rats. Fluorine produced a selective toxic action on the tissues of the permanently growing incisors causing disturbances of the dentine- and amelogenesis, and also derangement of the pulp circulation. Changes in the bone tissue of the jaws were characterized by the progressive porosity phenomena. It appeared that regress of the process required a definite duration of the restorative period.     

Proliferative capacity of enterochromaffin cells in guinea-pigs with experimental ileitis

Enterochromaffin (EC) cells regulate gut motility and secretion in response to luminal stimuli, via the release of serotonin (5-HT). Inflammatory bowel disease and other gastrointestinal disorders are associated with increased numbers of EC cells and 5-HT availability. Our aim was to determine whether proliferation of EC cells contributed to the hyperplasia associated with intestinal inflammation. Ileitis was induced in guinea-pigs by intraluminal injection of 2,4,6-trinitrobenzene sulphonic acid (TNBS). A single pulse of 5-bromo-2′-deoxyuridine (BrdU) was injected 1 or 24 h before the collection of tissue, 6 or 7 days after TNBS treatment. In the controls, the labelling index (percentage of BrdU-labelled EC cells) was less than 1%. Despite a significant increase in EC cells in the inflamed ileum, the labelling index was similar in the TNBS-treated animals to that of controls. An increased occurrence of EC cells in the BrdU-labelled zone accounted for the increase in EC cells in the inflamed ileum. Goblet cell numbers were also significantly increased in the inflamed ileum, indicating that cell hyperplasia was not limited to the enteroendocrine cell lineage. This study demonstrates that a small portion of EC cells retain some proliferative capacity; however, hyperplasia associated with ileitis is not attributable to the increased proliferation of EC cells and is not limited to one cell lineage. Therefore, EC cell hyperplasia most probably occurs at the level of the stem cell or recruitment from the progenitor pool. This work was supported by an operating grant from the Crohn’s and Colitis Foundation of Canada (CCFC; to Keith Sharkey and Dr. Gary Mawe, University of Vermont, USA). Keith Sharkey is an Alberta Heritage Foundation for Medical Research (AHFMR) Medical Scientist and the CCFC Chair in Inflammatory Bowel Disease Research. Jennifer O’Hara is an AHFMR graduate student.     

T cell subsets and IFN-gamma production in resistance to systemic candidosis in immunized mice

In addition to previous evidence for the roles of T cell-dependent immunity and delayed-type hypersensitivity in acquired resistance to systemic candidosis in mice, in the present study we have investigated the relative contributions of L3T4+ and Lyt-2+ lymphocytes in the protective immunity induced by vaccination with low virulence Candida albicans cells. We have also addressed the issue of the mode of Candida Ag recognition by specific T cells leading to cytokine release. Spleen cells from immunized mice produced high levels of IFN-gamma in vitro in response to Candida Ag, and this activity was abolished only by the combined treatment of the responder population with anti-L3T4 and anti-Lyt-2.2 mAb plus C. Positively selected L3T4+ and Lyt-2+ cells also produced IFN-gamma in vitro, provided accessory cells (plastic-adherent and Thy-1- Ia- splenocytes, respectively) were added to the lymphocyte-yeast cell cocultures. The production of IFN-gamma by purified L3T4+ and Lyt-2+ cells was inhibited by addition of the respective anti-class II and anti-class I H-2 antibody to the cultures. In vivo, administration of anti-L3T4, anti-Lyt-2.2 mAb or a combination of both significantly impaired the resistance of immunized mice to challenge with virulent C. albicans, as manifested by increased recovery of the yeast from the mouse kidneys. A similar effect was observed upon neutralization of endogenous IFN-gamma by treatment with rat mAb. These results suggest that both L3T4+ and Lyt-2+ T cells play a role in acquired immunity to systemic C. albicans infection, and that their activity may involve IFN-gamma-mediated stimulation of candidacidal mechanisms.     

Topical treatment with eberconazole of the experimental guinea pig cutaneous candidosis.

Eberconazole is a new azole antifungal drug for topical treatment of superficial mycoses. The usefulness of this drug was evaluated in an experimental model of cutaneous candidosis in guinea pigs comparing with the classical clotrimazole in a single blind trial. Twenty-five animals were inoculated in two symmetrical areas of the back with Candida albicans developing skin infection. One group of 10 animals were treated once per day with clotrimazole 1% cream in one side and with excipient in the other. Other group of 10 guinea pigs received eberconazole 1% cream and excipient. Five animals did not receive any treatment and were used as controls. After five days of treatment most lesions cured or improved and cultures were negative when clotrimazole or eberconazole were applied. Seventy per cent of lesions treated with excipient were clinically improved and 10% cured, but 85% of cultures remained positive for C. albicans. The therapeutic efficacy of eberconazole 1% cream was similar to clotrimazole 1% cream in the guinea ping model of cutaneous candidosis. Tolerance of both drugs was excellent. These results suggest the usefulness of eberconazole in human cutaneous infections due to C. albicans.     

Effect of streptomycin and kanamycin on the course of experimental tularaemia in guinea-pigs

1. (1)
   Guinea-pigs weighing 250–300 g. were treated with daily doses of 10 mg. streptomycin and kanamycin for one and two weeks, starting one, four and seven days after subcutaneous infection with a dose of 10 or 100 MLD of a virulent strain ofPasteurella tularensis; 88–96% were protected from death. The adminis-tration of streptomycin 48 hours before or 24 hours after infection with a sublethal dose had a similar protective effect.     
   
   

An investigation of the role of true hypha production in the pathogenesis of experimental oral candidosis

From 427 cases of human oral candidosis 2135 yeast clones were screened for the presence of germ tube-negative C. albicans and variants that formed only pseudohyphae in serum; one strain of each was found. The pathogenic potential of the serum-pseudohyphal and germ tube-negative C. albicans variants was investigated in the oral cavity of the rat; both variants failed to induce palatal candidosis, in contrast to a germ tube-positive C. albicans control strain. The pathogenic potential of C. albicans strains appears to be dependent on the formation of true germ tubes.     

Cutaneous candidosis in immunosuppressed patients

One-hundred patients with candidosis of the skin, mucous membranes and nail plates (confirmed by cultivation) were examined. Topical or systemic antimycotic treatment was successful in 58 patients. After a complete evaluation, 42 patients were found to suffer from factors supporting candidosis —diabetes mellitus (12), anemia (3) and various local factors (10 patients); 27 patients showed a deficiency in cell-mediated immunity. In addition to intensive antimycotic therapy, successful treatment is affected by the actual immunity level and can be ensured by efficient immunomodulation treatment of immuno-deficiency.     

Multiple actions of systemic artemin in experimental neuropathy

The clinical management of neuropathic pain is particularly challenging. Current therapies for neuropathic pain modulate nerve impulse propagation or synaptic transmission; these therapies are of limited benefit and have undesirable side effects. Injuries to peripheral nerves result in a host of pathophysiological changes associated with the sustained expression of abnormal pain. Here we show that systemic, intermittent administration of artemin produces dose- and time-related reversal of nerve injury-induced pain behavior, together with partial to complete normalization of multiple morphological and neurochemical features of the injury state. These effects of artemin were sustained for at least 28 days. Higher doses of artemin than those completely reversing experimental neuropathic pain did not elicit sensory or motor abnormalities. Our results indicate that the behavioral symptoms of neuropathic pain states can be treated successfully, and that partial to complete reversal of associated morphological and neurochemical changes is achievable with artemin.     

Experimental chronic vaginal candidosis in rats

In the past, the rat model of experimental vaginal candidosis has been used to study the efficacy of antifungal agents in eradicating acute vaginitis. In the present study, chronic vaginal candidosis was induced to study the natural history of the infection. Results indicate that chronic infection is readily achieved and is strictly dependent on oophorectomy and hormonal maintenance of pseudoestrous. Histologic studies confirm that rats so infected and with long term vaginal carriage of Candida albicans have true chronic infection with extensive mycelial formation and superficial mucosal invasion.